ansys icepak tutorials

ANSYS Icepak Tutorials

Release 14.0ANSYS, Inc.

November 2011Southpointe

275 Technology Drive

Canonsburg, PA 15317 ANSYS, Inc. is

certified to ISO

9001:[email protected]

http://www.ansys.com

(T) 724-746-3304

(F) 724-514-9494

Copyright and Trademark Information

© 2011 SAS IP, Inc. All rights reserved. Unauthorized use, distribution or duplication is prohibited.

ANSYS, ANSYS Workbench, Ansoft, AUTODYN, EKM, Engineering Knowledge Manager, CFX, FLUENT, HFSS and any

and all ANSYS, Inc. brand, product, service and feature names, logos and slogans are registered trademarks or

trademarks of ANSYS, Inc. or its subsidiaries in the United States or other countries. ICEM CFD is a trademark used

by ANSYS, Inc. under license. CFX is a trademark of Sony Corporation in Japan. All other brand, product, service

and feature names or trademarks are the property of their respective owners.

Disclaimer Notice

THIS ANSYS SOFTWARE PRODUCT AND PROGRAM DOCUMENTATION INCLUDE TRADE SECRETS AND ARE CONFID-

ENTIAL AND PROPRIETARY PRODUCTS OF ANSYS, INC., ITS SUBSIDIARIES, OR LICENSORS. The software products

and documentation are furnished by ANSYS, Inc., its subsidiaries, or affiliates under a software license agreement

that contains provisions concerning non-disclosure, copying, length and nature of use, compliance with exporting

laws, warranties, disclaimers, limitations of liability, and remedies, and other provisions. The software products

and documentation may be used, disclosed, transferred, or copied only in accordance with the terms and conditions

of that software license agreement.

ANSYS, Inc. is certified to ISO 9001:2008.

U.S. Government Rights

For U.S. Government users, except as specifically granted by the ANSYS, Inc. software license agreement, the use,

duplication, or disclosure by the United States Government is subject to restrictions stated in the ANSYS, Inc.

software license agreement and FAR 12.212 (for non-DOD licenses).

Third-Party Software

See the legal information in the product help files for the complete Legal Notice for ANSYS proprietary software

and third-party software. If you are unable to access the Legal Notice, please contact ANSYS, Inc.

Published in the U.S.A.

Table of Contents

1. Using This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1.What's In This Manual ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2. How To Use This Manual ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2.1. For the Beginner .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2.2. For the Experienced User .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3.Typographical Conventions Used In This Manual ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.4. Mouse Conventions Used In This Manual ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.5. When To Call Your ANSYS Icepak Support Engineer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Finned Heat Sink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3. Problem Description .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.4. Step 1: Create a New Project ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.5. Step 2: Build the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.6. Step 3: Generate a Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.7. Step 4: Physical and Numerical Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.8. Step 5: Save the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.9. Step 6: Calculate a Solution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.10. Step 7: Examine the Results ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.11. Step 8: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.12. Step 9: Additional Exercise .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

3. RF Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.3. Problem Description .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.4. Step 1: Create a New Project ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.5. Step 2: Build the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.6. Step 3: Create Assemblies .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53


3.8. Step 5: Physical and Numerical Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

3.9. Step 6: Save the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.10. Step 7: Calculate a Solution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.11. Step 8: Examine the Results ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

3.12. Step 9: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

4. Use of Parameterization to Optimize Fan Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

4.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

4.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71




4.6. Step 3: Creating Separately Meshed Assemblies .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83


4.8. Step 5: Setting up the Multiple Trials ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

4.9. Step 6: Creating Monitor Points ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

4.10. Step 7: Physical and Numerical Setting .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.11. Step 8: Save the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88


4.13. Step 10: Examine the Results ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

4.14. Step 11: Reports ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.15. Step 12: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

iiiRelease 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

of ANSYS, Inc. and its subsidiaries and affiliates.

4.16. Step 13: Additional Exercise to Model Higher Altitude Effect ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

5. Cold-Plate Model with Non-Conformal Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

5.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

5.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97




5.6. Step 3: Create a Separately Meshed Assembly .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

5.7. Step 4: Generate a Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

5.8. Step 5: Physical and Numerical Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103


5.10. Step 7: Calculate a Solution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105


5.12. Step 9: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

5.13. Step 10: Additional Exercise .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

6. Heat-Pipe Modeling and Nested Non-Conformal Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.3. Problem Description .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.4. Step 1: Create a New Project ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

6.5. Step 2: Build the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

6.6. Step 3: Create Nested Non-conformal Mesh Using Assemblies .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113






6.12. Step 9: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

7. Non-Conformal Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

7.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

7.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121




7.6. Step 3: Generate a Conformal Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124





7.11. Step 8: Add an Assembly to the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

7.12. Step 9: Generate a Non-conformal Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

7.13. Step 10: Save the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

7.14. Step 11: Calculate a Solution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

7.15. Step 12: Examine the Results ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

7.16. Step 13: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

8. Mesh and Model Enhancement Exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8.1. Objective .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8.3. Skills Covered .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8.4. Training Method Used .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8.5. Loading the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8.6. A 15 Minute Exploration .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Release 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.iv


8.7. Step-by-Step Approach .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

8.8. Modification 1: Non-Conformal Mesh of the Heat Sink and Components .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

8.9. Modification 2: Resolution of Thin Conducting Plate Intersecting Non-Conformal Region .... . . . . . . . . . . . . 137

8.10. Modification 3: Non-Conformal Mesh for the hi-flux-comps Cluster ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

8.11. Modification 4: A Super Assembly... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

8.12. Modification 5: A Simplification Based on Magnitudes of Resistances... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

8.13. Modification 6: A Classic Case for Thin Conducting Plate... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

8.14. Conclusion .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

9. Loss Coefficient for a Hexa-Grille . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

9.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

9.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143




9.6. Step 3: Define Parameters and Trials ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146






9.12. Step 9: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

10. Inline or Staggered Heat Sink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

10.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

10.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

10.3. Problem Description .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

10.4. Step 1: Create a New Project ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

10.5. Step 2: Build the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

10.6. Step 3: Define Design Variables .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

10.7. Step 4: Define Parametric Runs and Assign Primary Functions .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

10.8. Step 5: Generate a Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

10.9. Step 6: Physical and Numerical Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166


10.11. Step 8: Define Monitor Points ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166


10.13. Step 10: Examine the Results ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

10.14. Step 11: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

11. Minimizing Thermal Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

11.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

11.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173




11.6. Step 3: Define Design Variables .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175



11.9. Step 6: Save the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

11.10. Step 7: Define Primary, Compound, and Objective Functions .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178



11.13. Step 10: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

11.14. Step 11: Additional Exercise .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

12. Radiation Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

vRelease 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information



12.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

12.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185






12.8. Step 5: Solving the Model Without Radiation .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193


12.10. Step 7: Calculate a Solution- No Radiation .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

12.11. Step 8: Surface to Surface (S2S) Radiation Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

12.12. Step 9: Discrete Ordinates (DO) Radiation Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

12.13. Step 10: Ray Tracing Radiation Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197


12.15. Step 12: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

13. Transient Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

13.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

13.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201








13.10. Step 8: Generate a Summary Report ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207


13.12. Step 10: Examine Transient Results in CFD Post ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

13.13. Step 10: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

14. Zoom-In Modeling in ANSYS Workbench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

14.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

14.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217









14.11. Step 8: Create a Zoom-In Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

14.12. Step 9: Edit the Zoom-in Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

14.13. Step 10: Mesh the Zoom-In Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

14.14. Step 11: Zoom-In Physical and Numerical Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

14.15. Step 12: Examine the Zoom-in Results ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

14.16. Step 13: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

14.17. Step 14: Additional Exercise 1 .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

14.18. Step 15: Additional Exercise 2 .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

15. IDF Import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

15.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

15.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235


Release 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.vi




15.6. Step 3: Component Filtration Alternatives .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

15.7. Step 4: Component Models Alternatives .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

15.8. Step 5: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

16. Modeling CAD Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

16.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

16.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245


16.4. Step 1: Creating a New Project ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246







16.11. Step 8: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

17. Trace Layer Import for Printed Circuit Boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

17.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

17.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267




17.6. Conduction Only Model (PCB Without the Components) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276


17.8. Step 2: Set Physical and Numerical Values .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277




17.12. PCB With the Actual Components Under Forced Convection .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

17.13. Step 1: Generate a Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

17.14. Step 2: Set Physical and Numerical Values .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280



17.17. Using the Model Layers Separately Option .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

17.18. Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

17.19. Additional Exercise 1 .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

17.20. Additional Exercise 2 .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

18. Joule/Trace Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

18.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

18.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283









18.11. Step 8: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

19. Microelectronics Packages - Compact models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

19.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

viiRelease 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information



19.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295









19.11. Step 8: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310

19.12. Step 9: Additional Exercise .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310

20. Multi-Level Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.1. Objective .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.3. Skills Covered .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.4. Training Method Used .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.5. Loading the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.6. Step-by-Step Approach .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

20.7. Modification 1: Multi-Level Meshing of the Fan_Guide .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

20.8. Modification 2: Multi-Level Mesh of the Sheetmetal_hs_assy.1 .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315

20.9. Generate a Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316

20.10. Conclusion .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

21. Characterizing a BGA-package by Utilizing ECAD Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

21.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

21.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321









21.11. Step 8: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

22. Zero Slack with Non-Conformal Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331

22.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331

22.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331



22.5. Step 2: Default Units ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333


22.7. Step 4: Import Traces .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333

22.8. Step 5: Add Slack Values .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

22.9. Step 6: Generate Mesh (with Slack Values) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

22.10. Step 7: Zero Slack .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336

22.11. Step 8: Generate Mesh (with Zero Slack) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

22.12. Step 9: Physical and Numerical Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

22.13. Step 10: Save the Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

22.14. Step 11: Calculate a Solution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338


22.16. Step 13: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

23. ANSYS Icepak - ANSYS Workbench IntegrationTutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

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23.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

23.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339








23.10. Step 7: Examine the Results with CFD-Post ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347

23.11. Step 8: Thermo-Mechanical Structural Analysis ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349

23.12. Step 9: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349

24. Postprocessing Using ANSYS CFD-Post . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351

24.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351

24.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351



24.5. Step 2: Parametric Trials and Solver Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354


24.7. Step 4: Postprocessing Using ANSYS CFD-Post ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

24.8. Step 5: Comparison Study .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

24.9. Step 6: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383

25. High Density Datacenter Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385

25.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385

25.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385



25.5. Step 2: Set Preferences .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387



25.8. Step 5: Create Monitor Points ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413





25.13. Step 10: Additional Exercise: Visualize and analyze the results in ANSYS CFD-Post ... . . . . . . . . . . . . . . . . . . . . . 424

25.14. Step 11: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424

26. Design Modeler - Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425

26.1. Introduction .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425

26.2. Prerequisites .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425




26.6. Step 3: Add Shortcuts to the Toolbar .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427

26.7. Step 4: Edit the Model for ANSYS Icepak .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428

26.8. Step 5: Opening the Model in ANSYS Icepak .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445

26.9. Step 6: Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447

Index .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449

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Chapter 1: Using This Manual

1.1. What's In This Manual

This manual contains tutorials that teach you how to use ANSYS Icepak to solve different types of

problems. In each tutorial, features related to problem setup and postprocessing are demonstrated.

The tutorial "Finned Heat Sink" provides detailed instructions designed to introduce the beginner to

ANSYS Icepak. This tutorial provides explicit instructions for all steps in the problem setup, solution,

and postprocessing. The remaining tutorials assume that you have read or solved the tutorial "Finned

Heat Sink", or that you are already familiar with ANSYS Icepak and its interface. In these tutorials, some

steps will not be shown explicitly. The input files are available in the installation area and available for

download on the ANSYS Customer Portal.

1.2. How To Use This Manual

Depending on your familiarity with computational fluid dynamics and ANSYS Icepak, you can use this

tutorial guide in a variety of ways:

1.2.1. For the Beginner

1.2.2. For the Experienced User

1.2.1. For the Beginner

If you are a beginning user of ANSYS Icepak, you should first read and solve the tutorial "Finned Heat

Sink", in order to familiarize yourself with the interface and with basic setup and solution procedures.

You may then want to try a tutorial that demonstrates features that you are going to use in your applic-

ation. For example, if you are planning to solve a problem involving radiation, you should look at the

tutorial "Radiation Modeling".

You may want to refer to other tutorials for instructions on using specific features, such as grouping

objects, even if the problem solved in the tutorial is not of particular interest to you.

1.2.2. For the Experienced User

If you are an experienced ANSYS Icepak user, you can read and/or solve the tutorial(s) that demonstrate

features that you are going to use in your application. For example, if you are planning to solve a

problem involving radiation, you should look at the tutorial "Radiation Modeling".

You may want to refer to other tutorials for instructions on using specific features, such as grouping

objects, even if the problem solved in the tutorial is not of particular interest to you.

1.3. Typographical Conventions Used In This Manual

Several typographical conventions are used in this manual's text to facilitate your learning process.

• Different type styles are used to indicate graphical user interface menu items and text inputs that you

enter (e.g., Open project panel, enter the name projectname ).

1Release 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information


http://www1.ansys.com/customer

• A mini flow chart is used to indicate the menu selections that lead you to a specific panel. For example,

Model → Generate mesh

indicates that the Generate mesh option can be selected from the Model menu at the top of the

ANSYS Icepak main window.

The arrow points from a specific menu toward the item you should select from that menu.

• A mini flow chart is also used to indicate the list tree selections that lead you to a specific panel or

operation. For example,

Problem setup → Basic parameters

indicates that the Basic parameters item can be selected from the Problem setup node in the

Model manager window

• Pictures of toolbar buttons are also used to indicate the button that will lead you to a specific panel.

For example, indicates that you will need to click on this button (in this case, to open the Walls

panel) in the toolbar.

1.4. Mouse Conventions Used In This Manual

The default mouse buttons used to manipulate your model in the graphics window are described in

Manipulating Graphics With the Mouse in the Icepak User's Guide. Although you can change the mouse

controls in ANSYS Icepak to suit your preferences, this manual assumes that you are using the default

settings for the mouse controls. If you change the default mouse controls, you will need to use the

mouse buttons you have specified instead of the mouse buttons that the manual tells you to use.

1.5. When To Call Your ANSYS Icepak Support Engineer

The ANSYS Icepak support engineers can help you to plan your modeling projects and to overcome

any difficulties you encounter while using ANSYS Icepak. If you encounter difficulties we invite you to

call your support engineer for assistance. However, there are a few things that we encourage you to

do before calling:

1. Read the section(s) of the manual containing information on the options you are trying to use.

2. Recall the exact steps you were following that led up to and caused the problem.

3. Write down the exact error message that appeared, if any.

4. For particularly difficult problems, package up the project in which the problem occurred (see Packing

and Unpacking Model Files in the Icepak User's Guide for instructions) and send it to your support en-

gineer. This is the best source that we can use to reproduce the problem and thereby help to identify

the cause.

Release 14.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.2

Chapter 1: Using This Manual

Chapter 2: Finned Heat Sink

2.1. Introduction

This tutorial demonstrates how to model a finned heat sink using ANSYS Icepak.

In this tutorial you will learn how to:

• Create a new project.

• Create blocks, openings, fans, sources, and plates.

• Include effects of turbulence in the simulation.

• Calculate a solution.

• Examine contours and vectors on object faces and on cross-sections of the model.

2.2. Prerequisites

This tutorial assumes that you have little to no experience with ANSYS Icepak and so each step will be

explicitly described.

2.3. Problem Description

The cabinet contains an array of five high-power devices, a backing plate, ten fins, three fans, and a

free opening, as shown in Figure 2.1 (p. 4). The fins and backing plate are constructed of extruded

aluminum. Each fan has a total volume flow rate of 18 cfm and each source dissipates power at the rate

of 33 W. According to the design objective, the base of the devices should not exceed 65°C when the

fins are swept with air at an ambient temperature of 20°C.



Figure 2.1 Problem Specification

2.4. Step 1: Create a New Project

1. Start ANSYS Icepak, as described in Starting ANSYS Icepak in the Icepak User's Guide.

When ANSYS Icepak starts, the Welcome to Icepak panel opens automatically.

2. Click New in the Welcome to Icepak panel to start a new ANSYS Icepak project.

The New project panel appears.



3. Specify a name for your project and click Create.

ANSYS Icepak creates a default cabinet with the dimensions 1 m × 1 m × 1 m, and displays the

cabinet in the graphics window.

Note

You can rotate the cabinet around a central point using the left mouse button, or you

can translate it to any point on the screen using the middle mouse button. You can

zoom into and out from the cabinet using the right mouse button. To restore the

cabinet to its default orientation, select Home position in the Orient menu.

2.5. Step 2: Build the Model

To build the model, you will first resize the cabinet to its proper size. Then you will create the backing

plate and opening, followed by the elements that will be duplicated (i.e., the fans, fins, and devices).

1. Resize the default cabinet in the Cabinet panel.

Model → Cabinet



Step 2: Build the Model

Extra

You can also open the Cabinet panel by selecting the Cabinet item in the Model

manager window and then clicking the Edit object button ( ) in the Object modi-

fication toolbar. Resizing of the cabinet object can also be done in the geometry

window in the lower right hand corner of the GUI.

a. In the Cabinet panel, click the Geometry tab.

b. Under Location, enter the following coordinates:

0.075xE0xS

0.25yE0yS

0.356zE0zS

c. Click Done to resize the cabinet and close the panel.

d. In the Orient menu, select Scale to fit to scale the view of the cabinet to fit the graphics window.

Extra

You can also scale the view by clicking the Scale to fit button ( ).



Extra

After selecting the object to be edited in the model tree, there are several ways

you can open the Edit panel:

• Double-click on the object in the model tree, or

– Type Ctrl+e, or

– Right-click the object in the model tree and scroll to Edit object, or

– Click the Edit button in the object geometry window, or

– Click the Edit icon ( ) in the model toolbar.

2. Create the backing plate.

The backing plate is 0.006 m thick and divides the cabinet into two regions: the device side (where

the high-power devices are contained in a housing) and the fin side (where the fins dissipate heat

generated by the devices). The backing plate is represented in the model by a solid prism block.

Extra

Blocks allow six-sided control for meshing and thermal specifications, whereas plates

allow for only two-sided control.

a. Click the Create blocks button ( ) to create a new block.

ANSYS Icepak creates a new solid prism block in the center of the cabinet. You need to change

the size of the block.

b. Click the Edit object button ( ) to open the Blocks panel.

c. Click the Geometry tab.

d. Enter the following coordinates for the block:

0.006xE0xS

0.25yE0yS

0.356zE0zS




e. Click Done to modify the block and close the panel.

3. Create the free opening on the fin side of the backing plate.

a. Click the Create openings button ( ) to create a new opening.

ANSYS Icepak creates a free rectangular opening lying in the x-y plane in the center of the

cabinet. You need to change the size of the opening.

b. Click the Edit object button ( ) to open the Openings panel.


d. Enter the following coordinates for the opening:

0.075xE0.006xS

0.25yE0yS

—zE0.356zS



e. Click Done to modify the opening and close the panel.

4. Create the first fan.

Each fan is physically identical to the others, except with respect to its location on the cabinet

wall. To create the set of three fans, you will build a single fan as a template, and then create two

copies, each with a specified offset in the y direction.

a. Click the Create fans button ( ) to create a new fan.

ANSYS Icepak creates a free circular fan lying in the x - y plane in the center of the cabinet.

You need to change the size of the fan and specify its mass flow rate.

b. Click the Edit object ( ) to open the Fans panel.


d. Enter the following coordinates for the fan:

0.04xC

0.0475yC

0zC

e. Enter 0.03 for the external radius (Radius), and 0.01 for the internal radius (Int Radius).




f. Click the Properties tab.

g. Keep the default Fan type of intake.

h. Under the Fan flow tab, select Fixed and Volumetric. Enter a volume flow rate of 18 cfm.

Note

Make sure to update the units to cfm by clicking on the triangle button and select-

ing cfm from the drop-down list.



i. Click Done to modify the fan and close the panel.

5. Copy the first fan (fan.1) to create the second and third fans (fan.1.1 and fan.1.2).

a. In the graphics display window, select fan.1 using the Shift key and right mouse button.

b. In the object context menu, select Copy and the Copy fan fan.1 panel opens.

c. Enter 2 as the Number of copies.

d. Enable the Translate option and specify a Y offset of 0.0775 m.




e. Click Apply.

ANSYS Icepak makes two copies of the original fan, each offset by 0.0775 m in the y direction

from the previous one.

6. Create the first high-power device.

Like the fans, each device is physically identical to the others, except with respect to its location

in the cabinet. To create the set of five devices, you will build a single rectangular planar source

as a template, and then create four copies, each with a specified offset in the y direction.

a. Click the Create sources button ( ) to create a source.

ANSYS Icepak creates a free rectangular source in the center of the cabinet. You need to

change the geometry and size of the source and specify its heat source parameters.

Note

For planar objects, select the desired plane first, then enter the coordinates.

b. Click the Edit object button ( ) to open the Sources panel.


d. Keep the default selection of Rectangular.

e. In the Plane drop-down list, select Y-Z.

f. Enter the following coordinates for the source:

—xE0xS

0.0385yE0.0315yS



0.2005zE0.1805zS

g. Click the Properties tab.

h. Under Thermal specification, set the Total power to 33 W.




i. Click Done to modify the source and close the panel.

7. Copy the first device (source.1) to create the other four devices (source.1.1, source.1.2, source.1.3,

and source.1.4).

a. In the Model manager window, select the source.1 item under the Model node.

b. Click the Copy object button ( ).

c. Follow the same instructions that you used above to copy the fans, using a Y offset of 0.045 m

to create 4 copies.

8. Create the first fin.

Like the fans and devices, each fin is physically identical to the others, except with respect to its

location in the cabinet. To create the array of ten fins, you will build a single rectangular plate as

a template, and then create nine copies, each with a specified offset in the y direction.

a. Click the Create plates button ( ) to create a plate.

ANSYS Icepak creates a free rectangular plate in the x-y plane in the center of the cabinet.

You need to change the orientation and size of the plate and specify its thermal parameters.

b. Click the Edit object button ( ) to open the Plates panel.


d. In the Plane drop-down list, select X-Z.

e. Enter the following coordinates for the plate:



0.075xE0.006xS

—yE0.0125yS

0.331zE0.05zS

f. Click the Properties tab.

g. Under Thermal model, select Conducting thick from the drop-down menu.

h. Set the Thickness to 0.0025 m.

i. Keep default as the Solid material.

Note

Since the default solid material is extruded aluminum, you need not specify the

material explicitly here.




j. Click Done to modify the plate and close the panel.

9. Copy the first fin (plate.1) to create the other nine fins (plate.1.1, plate.1.2, ..., plate.1.9).

a. In the Model manager window, select the plate.1 item under the Model node.

b. Click the Copy object button ( ).

c. Follow the same instructions that you used above to copy the fans, using a Y offset of 0.025 m

to create 9 copies.

The completed model will look like Figure 2.2 (p. 17), which is shown in the Isometric view

(available in the Orient menu or by clicking the Isometric view button ( )).

Note

You can remove the object names by clicking the Display object names button ( ).



Figure 2.2 Completed Model for the Finned Heat Sink

10. Check the model to be sure that there are no problems (e.g., objects that are too close together to

allow for proper mesh generation).

Model → Check model

Note

You can also click the Check model button ( ) to check the model.

Note

ANSYS Icepak should report in the Message window that 0 problems were found.

11. Check the definition of the modeling objects to ensure that you specified them properly.

View → Summary (HTML)

The HTML version of the summary displays in your web browser. The summary displays a list of

all the objects in the model and all the parameters that have been set for each object. You can

view the detailed version of the summary by clicking the appropriate object names or property

specifications. If you notice any incorrect specifications, you can return to the appropriate modeling

object panel and change the settings in the same way that you originally entered them.




2.6. Step 3: Generate a Mesh

You will generate the mesh in two steps. First you will create a coarse mesh and examine it to determine

where further mesh refinement is required. Then you will refine the mesh based on your observations

of the coarse mesh.

Extra

For more information on how to refine a mesh locally, refer to Refining the Mesh Locally in

the Icepak User's Guide.


Extra

You can also generate a mesh by clicking the Generate mesh button ( ), which opens the

Mesh control panel.

1. Generate a coarse (minimum-count) mesh.

a. In the Mesh control panel, select Coarse in the Mesh parameters drop-down list.

ANSYS Icepak updates the panel with the default meshing parameters for a coarse (minimum-

count) mesh, shown in the panel below.

b. Set the Mesh units and all the Minimum gap units to mm.

c. Set the Minimum gap to 1 mm for X, Y, and Z.

d. Set the Max X size to 3.5, the Max Y size to 12.5, and the Max Z size to 17.5.



e. Click the Generate button to generate the coarse mesh.

Note

If the Allow minimum gap changes option is unchecked under the Misc tab,

ANSYS Icepak will inform you that your minimum object separation is more than

10% of the smallest size object in the model . You can stop the meshing process,

ignore the warning, or allow ANSYS Icepak to correct the values.

f. If this warning appears, click Change value and mesh in the Minimum separation in x and

Minimum separation in y panels to accept the recommended changes to your model and con-

tinue generating the mesh.

2. Examine the coarse mesh on a cross-section of the model.

a. Click the Display tab.



Step 3: Generate a Mesh

b. Turn on the Cut plane option.

c. In the Set position drop-down list, select X plane through center.

d. Turn on the Display mesh option.

The mesh display plane is perpendicular to the fins, and aligned with the devices, as shown

in Figure 2.3 (p. 21).

Note

The number of elements may vary slightly on different machines.



Figure 2.3 Coarse Mesh on the y-z Plane

e. Use the slider bar to move the plane cut through the model. See Figure 2.4 (p. 22) to examine a

close-up view of the coarse mesh.

Note

You can change the mesh color using the Surface mesh color and the Plane

mesh color options.

The mesh elements near the fins are too large to sufficiently resolve the problem physics. In

the next step, you will generate a finer mesh.

3. Generate a finer mesh.

a. Click the Settings tab.

b. Under Global, select Normal in the Mesh parameters drop-down list.

ANSYS Icepak updates the panel with the default meshing parameters and Minimum gap

values for a “normal" (i.e., finer than coarse) mesh.

4. Click the Generate button in the Mesh control panel to generate the finer mesh.

5. Examine the new mesh.

The graphics display updates automatically to show the new mesh. Click the Display tab and use

slider bar to advance the plane cut and view the mesh throughout the model.




Figure 2.4 Fine and Coarse Mesh on the y-z Plane

6. Turn off the mesh display.

a. Click the Display tab in the Mesh control panel.

b. Deselect the Display mesh option.

c. Click Close to close the Mesh control panel.



Note

After deselecting the Display mesh option and closing the Mesh control panel,

you can display the mesh on selected objects by using the context menu in the

graphics display window. To display the context menu, hold down the Shift key

and press the right mouse button anywhere in the graphics window, but not on

an object. Select Display mesh and select the object you want it displayed on.

Figure 2.5 Display mesh option

2.7. Step 4: Physical and Numerical Settings

Before starting the solver, you will first review estimates of the Reynolds and Peclet numbers to check

that the proper flow regime is being modeled.

1. Check the values of the Reynolds and Peclet numbers.

Solution settings → Basic settings



Step 4: Physical and Numerical Settings

a. Click the Reset button. Reset calculates the Reynolds and Peclet numbers.

b. Check the values printed to the Message window.

The Reynolds and Peclet numbers are approximately 13,000 and 9,000, respectively, so the

flow is turbulent. ANSYS Icepak will recommend setting the flow regime to turbulent.

Note

These values are only estimates, based on the current model setup. Actual values

may vary, and may need to be verified, depending on your design.

c. Click Accept to save the solver settings.

2. Enable turbulence modeling.


a. In the Basic parameters panel, select Turbulent as the Flow regime.

b. Keep the default Zero equation turbulence model.

a. Turn radiation off by clicking Off under Radiation.



b. Click Accept to save the new settings.

2.8. Step 5: Save the Model

ANSYS Icepak automatically saves the model for you before it starts the calculation, but it is a good

idea to save the model (including the mesh) yourself as well. If you exit ANSYS Icepak before you start

the calculation, you will be able to open the job you saved and continue your analysis in a future ANSYS

Icepak session. (If you start the calculation in the current ANSYS Icepak session, ANSYS Icepak will simply

overwrite your job file when it saves the model.)

File → Save project

Note

Alternatively, you can click the button in the File commands toolbar.

2.9. Step 6: Calculate a Solution

1. Start the calculation.

Solve → Run solution

Note

You can click the Run solution button ( ) in the Model and solve toolbar.



Step 6: Calculate a Solution

2. Keep the default settings in the Solve panel.

3. Click Start solution to start the solver.

Note

There are no universal metrics for judging convergence, a good indicator is when the

solution no longer changes with more iterations and when the residuals have decreased

to a certain degree. The default criterion is that each residual will be reduced to a value

of less than −�

except the energy residual, for which the default criterion is −�

.

It is a good idea to judge convergence not only by examining residuals levels, but also

by monitoring relevant integrated quantities.

ANSYS Icepak begins to calculate a solution for the model, and a separate window opens where

the solver prints the numerical values of the residuals. ANSYS Icepak also opens the Solution re-

siduals graphics display and control window, where it displays the convergence history for the

calculation.

Upon completion of the calculation, your residual plot will look something like Figure 2.6 (p. 27).

You can zoom in the residual plot by using the left mouse.

Note

The actual values of the residuals may differ slightly on different machines, so your

plot may not look exactly the same as Figure 2.6 (p. 27).



Figure 2.6 Residuals

4. Click Done in the Solution residuals window to close it.

2.10. Step 7: Examine the Results

ANSYS Icepak provides a number of ways to view and examine the solution results, including:

• plane-cut views

• object-face views

The following steps illustrate how to generate and display each view.



Step 7: Examine the Results

Note

The objective of this exercise is to determine whether the air flow and heat transfer associated

with the heat sink (fans and fins) are sufficient to maintain device temperatures below 65°C.

You can accomplish this by creating different plane cuts and monitoring the velocity vector

and temperature on it. Plane-cut views allow you to observe the variation in a solution variable

across the surface of a plane.

You will use the Plane cut panel to view the direction and magnitude of velocity across a

horizontal plane.

1. To open the Plane cut panel, select Plane cut in the Post menu.

Extra

You can also open the Plane cut panel by clicking the Plane cut button ( ).

2. Display velocity vectors on a plane cut on the fin side of the enclosure.

Post → Plane cut

a. In the Name field, enter the name cut-velocity .

b. In the Set position drop-down list, select X plane through center.

Tip

Click the triangle button located next to the Set position text field to open the

drop-down list.

c. Turn on the Show vectors option.

d. Click Create.

e. In the Orient menu, select Orient positive X.



This orients the model as shown in Figure 2.7 (p. 29). You can see that the maximum velocity

occurs at the fan blades. The lowest velocity occurs between the top fin and the adjacent

cabinet wall, and between the bottom fin and the adjacent cabinet wall.

Extra

You can also select the positive � orientation by clicking the Orient positive X

button ( ).

Figure 2.7 Velocity Vectors on the Fin Side of the Enclosure

f. In the Plane cut panel, turn off the Active option.

This temporarily removes the velocity vector display from the graphics window, so that you

can more easily view the next postprocessing object.

Note

You can later open the Inactive folder in the model tree and locate cut_velo-city . cut_velocity can be either deleted or reactivated by dragging it to

Trash or to the Post-processing folder, as well as with the right-click dialog.

3. Display contours of temperature on the fin side of the enclosure.

a. Click New in the Plane cut panel.

b. In the Name field, enter the name cut-temperature .


d. Turn on the Show contours option and click Parameters.

The Plane cut contours panel opens.




e. Keep the default selection of Temperature.

f. For Shading options, keep the default selection of Banded.

g. For Color levels, select Calculated and then select This object from the drop-down list.

h. Click Apply.

ANSYS Icepak computes the color range for the display based on the range of temperatures

on this plane cut.

i. Click Done to save the new settings, close the panel, and update the graphics display.

The graphics display updates to show the temperature contour plot. The actual values of

temperature may slightly differ on different systems. You can use the scroll bar to change

the x-location of the plane cut. In addition, the plane cut can be dragged through the model

when you press the Shift key and hold down the middle mouse button on the plane. Ensure

you click the edge of the plane cut so as to not move any objects.

Figure 2.8 (p. 31) shows that heat conducts through the fins from the sources in both direc-

tions.



Figure 2.8 Temperature Contours on the Fin Side of the Enclosure

j. In the Plane cut panel, turn off the Active option.

4. Display velocity vectors superimposed with pressure contours.

a. Click New in the Plane cut panel.

b. In the Name field, enter the name cut-prvelocity .


d. Specify the display of velocity vectors.

i. Turn on the Show vectors option and click Parameters.

The Plane cut vectors panel opens.

ii. Select Fixed from the Color by drop-down list.

iii. Click on the square next to Fixed color and select black from the color palette.

iv. Click Done to close the panel.

e. Specify the display of contours of pressure.

i. Turn on the Show contours option and click Parameters.

The Plane cut contours panel opens.

ii. In the Plane cut contours panel, select Pressure in the Contours of drop-down list.

iii. For Shading options, keep the default selection of Banded.

iv. For Color levels, select Calculated and then select This object from the drop-down list.

v. Click Done to save the new settings, close the panel, and update the graphics display.

The graphics display updates to show the pressure contour plot superimposed on the

velocity vector plot.




Figure 2.9 (p. 32) shows isolated regions of high pressure immediately downstream of the

fans, including local maxima at the upstream tips of the fins.

Figure 2.9 Pressure Contours and Velocity Vectors on the Fin Side of the Enclosure

f. In the Plane cut panel, turn off the Active option.

5. Display contours of temperature on all five high-power devices.

An object-face view allows you to examine the distribution of a solution variable on one or more

faces of an object in the model. To generate an object-face view, you must select the object and

specify both the variable to be displayed (e.g., temperature) and the attributes of the view (e.g.,

shading type).

You will use the Object face panel to create a solid-band object-face view of temperature on all

five high-power devices and on the backing plate.

a. To open the Object face panel, select Object face in the Post menu.

Post → Object face

Extra

You can also open the Object face panel by clicking the Object face button ( ).

b. In the Name field, enter the name face-tempsource .

c. In the Object drop-down list, click source.1, hold down the Shift key, and click source.1.4 to

select all the sources, and click the Accept button.

d. Turn on the Show contours option.



e. Click Parameters next to the Show contours option.

The Object face contours panel opens.

f. In the Object face contours panel, keep the default selection of Temperature in the Contours

of drop-down list.

g. For Shading options, keep the default selection of Banded.

h. For Color levels, select Calculated and then select This object from the drop-down list.


The graphics display updates to show the temperature contours on the sources.

j. Use your right mouse button to zoom in and look more closely at each source.

Figure 2.10 (p. 34) shows a view with the temperature contours on all five sources. The tem-

perature distributions are similar for all sources: warm in the center and decreasing in tem-




perature toward the edges of the source. Temperature distributions on the top and bottom

sources are similar to each other, as are distributions on the two remaining sources.

Note

To view the temperature contours on an individual source, hold down the Shift

key and drag a box around a source object using the left mouse button. The source

object will show as highlighted in the Model manager window. Right click the

source object to display the context menu and select Create>Object

face(s)>Separate. The Object face panel is displayed for that particular object.

Change the settings to match the ones used above for all source objects and click

Create.

Figure 2.10 Temperature Contours on the Five Devices

k. In the Object face panel, turn off the Active option.

6. Display line contours of temperature on the backing plate.

a. Click New in the Object face panel.

b. In the Name field, enter the name face-tempblock .

c. In the Object drop-down list, select block.1 and click Accept.

d. Turn on the Show contours option and click Parameters.

The Object face contours panel opens.

e. In the Object face contours panel, keep the default selection of Temperature in the Contours

of drop-down list.

f. For Contour options, deselect Solid fill and select Line.

g. For Level spacing, select Fixed and set the Number of contour lines to 200 .

h. For Color levels, select Calculated and then select This object from the drop down list.




The graphics display updates to show the temperature contours on the block. Figure

2.11 (p. 35) shows that most of the heat is confined to the region near the sources. The

maximum temperature occurs near the middle three sources.

Figure 2.11 Temperature Contours on the Backing Plate

j. Click Done in the Object face panel to close the panel.

7. Save the post-processing objects created.

a. Select Save post objects to file in the Post menu.

b. Click on Save in the File selection window that opens.

Upon saving the project, all objects created during post-processing are saved within a

post_objects file for future retrieval.

Note

ANSYS Icepak does not automatically save the post-processing objects created in

the current session. When you exit ANSYS Icepak, they are deleted unless they are

saved using the above steps.

2.11. Step 8: Summary

In this tutorial, you set up and solved a model in order to determine the ability of the specified heat

sink to maintain source temperatures below 65 °C. Postprocessing results show that the maximum

source temperature is about 60 °C, indicating that the heat sink provides adequate cooling for the

sources.



Step 8: Summary

2.12. Step 9: Additional Exercise

To determine the effectiveness of the heat sink under conditions involving the failure of the middle

fan, deactivate or edit fan.1.1, go to the Properties tab and turn on Failed under the Options tab,

assign a free-area ratio of 0.3, and click Done. Next, remesh the model, solve it again using a different

solution ID, and examine the new results.

Note

When you are finished examining the results, you can end the ANSYS Icepak session by

clicking Quit in the File menu.

File → Quit



Chapter 3: RF Amplifier

3.1. Introduction

This tutorial demonstrates how to model an RF Amplifier using ANSYS Icepak.


• Create a new project.

• Create openings, fans, sources, enclosure, PCB, heat sink and walls.

• Use non-conformal meshing.

• Include effects of gravity and turbulence in the simulation.

• Calculate a solution.


3.2. Prerequisites

This tutorial assumes that you have little experience with ANSYS Icepak, but that you are generally fa-

miliar with the interface. If you are not, please review Sample Session in the Icepak User's Guide.


RF Amplifiers are typically sealed enclosures that are placed within larger systems. They present a

challenge from the thermal management perspective because no direct exchange of air exists between

the interior of the amplifier and the ambient. The common method of cooling such subsystems is to

mount a large heat sink on the amplifier housing that cools all the devices within the enclosure. A

simplified version of an RF amplifier (Figure 3.1 (p. 38)) will serve as the model for this tutorial. There

will be free convection inside the amplifier and forced convection in the external domain.



Figure 3.1 Schematic of the RF Amplifier


1. Start ANSYS Icepak, as described in Chapter 1 of the User's Guide.






3. Specify the name amplifier for your project and click Create.



Note






To build the model, you will first resize the cabinet to its proper size. Then you will create the amplifier

housing, devices (heat sources), PCB, heatsink, fan and other geometrical objects.

1. Resize the default cabinet and create an opening on one side of the cabinet.

Model → Cabinet

Select the cabinet in the Model tree and specify the following in the object geometry window:




Extra

After selecting the object to be edited in the model tree, there are several ways you

can open the Edit panel:

• Double-click on the object in the model tree, or

– Type Ctrl+e, or

– Right-click the object in the model tree and scroll to Edit object, or

– Click the Edit button in the object geometry window, or

– Click the Edit object icon ( ) in the model toolbar

Figure 3.2 The Cabinet Geometry Tab Panel

One side of this cabinet has an opening. Assign Properties on this boundary, in the Properties

tab of the Cabinet object panel (Figure 3.3 (p. 41)):

a. Change the Max y Wall type to be an Opening.

b. Click Done to accept the inputs and close the panel.



Figure 3.3 The Cabinet Boundary Panel

2. Create the Y and Z faces of the amplifier housing as an enclosure using the enclosure object.

Click on the Create enclosures icon ( ) in the model toolbar, then specify the following Name

and dimensions:

In the Properties tab specify the followings:

a. Change the Boundary type to Open for Min X and Max X. For others, retain the boundary type

as Thin.

b. Specify the Solid material as Polystyrene-rigid-R12.

Tip

You have to scroll down the list to find this material.

c. Click Done.




Figure 3.4 The Enclosure Panel

3. Create the Xmin face of the amplifier housing as a wall.

The wall covers the Xmin side of the enclosure.

4. Click on the Create walls icon ( ) in the model toolbar to create a new wall.

In the object edit window, name the wall Xmin and change the plane to Y-Z .

Note

While we will use the align tools to place the wall at the desired locations, we could

also specify the dimensions/locations of the wall in the Geometry tab and achieve the

same result. However, the align tools are faster, and thus are the recommended

method.

To start the process, left-click Morph Edges icon ( ) in the model toolbar. Now, follow the step-

by-step procedure described below:

a. Select the Zmax edge of the wall (Figure 3.5 (p. 43)) by left mouse clicking it in the graphical

window. Notice that it turns red to indicate that it has been selected.

b. Click the middle mouse button to accept this edge.

c. Select the lower Zmax edge of the enclosure (Figure 3.5 (p. 43)) with the left mouse button. Notice

that it turns yellow to indicate that it has been selected.



Figure 3.5 Schematic Showing Edge Identities for Alignment

d. Click the middle mouse button to accept the transformation. The wall Xmin should have now

been moved and resized. Now the wall should extend to the entire Xmin side of the enclosure.

To specify the remaining wall dimension, stay in the match edge mode and complete the following

steps:

a. Click the Zmin edge of the wall with the left mouse button. Be sure that it (and not the enclosure

edge) is highlighted in red. By repeatedly clicking the left mouse button, ANSYS Icepak cycles

through all possible edges.

b. Click the middle mouse button to accept.

c. Using the left mouse button, click the lower Zmin edge of the enclosure.

d. Click the middle mouse button to accept. The wall should now form the Xmin face of the enclosure.

e. Click the right mouse button to exit the Match edge mode.

The resulting model is shown in Figure 3.6 (p. 44) with shading to highlight new definitions.

Shading is available under the Info tab in most panels.




Figure 3.6 Geometry with Wall

Double-click on the newly created wall object (Xmin) in the model tree to open the Walls panel.

Now specify the following properties to the wall in the Properties tab.

a. Specify a Wall thickness of 1 mm (0.001 m).

b. Specify the Solid material as Polystyrene-rigid-R12 under Plastics.

c. Specify the External conditions as Heat transfer coefficient and click the Edit button.

The Wall external thermal conditions panel opens.



i. Select Heat transfer coefficient in the External conditions drop-down list and press Edit.

The Wall external thermal conditions panel opens.

ii. Set the Heat transfer coeff to 5 W/K-��

.

iii. Click Done to close the Wall external thermal conditions panel.

iv. Click Done to close Walls panel (Figure 3.7 (p. 45))

Figure 3.7 The Walls Panel

5. Create the PCB.

The PCB will cover the Xmax side of the enclosure.

a. Click on the Create printed circuit boards icon ( ) in the Model toolbar to create a PCB and

double click on the PCB object in the Model tree.

b. Specify the following in the geometry window:

c. Specify the Trace layer type as Detailed and input the parameters under Trace layer parameters

(make sure that you enter both columns) in the Properties tab as shown in Figure 3.8 (p. 46).

There are four internal layers.

Please notice that the Effective conductivity in plane and normal directions are updated

when you click on the Update button (Figure 3.8 (p. 46)).




Figure 3.8 The Printed circuit boards Panel

d. Click Done to close the Printed circuit boards panel.

6. Create the devices as 2D sources.

There are 12 devices on the bottom side of the PCB. Theses devices are created as 2D sources.

The following steps show you how to create one and then use the copy utility to create the re-

maining 11 sources.

a. Click on the Create sources icon ( ) in the model toolbar to create a source and double click

on the source object in the model tree.

b. Specify the following name, dimensions, and properties to the source.



c. In the Properties tab, specify the Total power as 7 W (Figure 3.9 (p. 47)) and click Done.

Figure 3.9 The Sources Panel

d. Create the other devices (sources) object by creating two copies of the device and translating it

to z= 0.055 m. Please follow the steps below for copying the source object.

i. Right mouse click on the source object and choose the Copy option.

ii. Specify the Number of copies as 2.

iii. Turn on the Translate option.

iv. Specify the Z offset to 0.055 m.

v. Click Apply to copy the object.




Figure 3.10 The Copy source device Panel

e. Similarly, create the other devices (sources) object by copying the sources created in the previous

steps.

i. Left mouse click and select device , then while holding down the Ctrl key, select device.1 ,

and device.2 . Right mouse click and choose the Copy option.

ii. Specify the Number of copies as 3.

iii. Turn on the Translate option.

iv. Specify the Y offset to 0.064 m.

v. Click Apply to copy the object.

Note

Following these two copy actions, you should now have 12 sources (Figure

3.11 (p. 49)) in a four rows by three columns pattern.



Figure 3.11 Geometry with Devices

7. Create the heat sink.

The extruded fin heat sink with the flow in the y direction will be created to remove the heat

from the PCB.

a. Click on the Create heat sinks icon ( ) in the Model toolbar to create a heat sink and double

click on the heat sink object in the model tree. Specify the following dimensions in the geometry

window.




b. In the heat sink object panel, select the Geometry tab, and specify a Base height of 0.004 m and

an Overall height of 0.04 m.

c. Specify the properties of the heat sink as shown in Figure 3.12 (p. 50) below. Note that we are

not changing parameters in the Flow/thermal data, Pressure loss, or Interface tabs.

Figure 3.12 The Heat sinks Panel

d. Click Done to close the Heat sinks panel.

8. Create the fan.

For this model, we will make use of ANSYS Icepak's fan library and search tool.

a. Select the Library tab in the model manager window(Figure 3.13 (p. 51)).

b. Right-click on Libraries in the model tree and choose Search fans.

The Search fan library dialog appears.

i. In the Physical tab, deactivate the Min fan size and enter 80 mm for the Max fan size.

ii. Select the Thermal/flow tab, enable the Min flow rate option and specify a Min flow rate

of 80 cfm.



Note

The minimum flow rate used in the search criteria implies the minimum free

flow of the fans.

iii. Click on the Search button.

Note

ANSYS Icepak lists all the fans in its libraries that satisfy these conditions.

c. Select the fan called delta.FFB0812_24EHE in the Name column by clicking on it with the

left mouse button.

d. Click Create to load the fan into the model.

Figure 3.13 Search Fan library Panel

e. Now, we need to specify the location of the fan created in the previous steps. Resize the fan

geometry based on the Figure 3.14 (p. 52) (note X-Z plane).




Figure 3.14 The Fans Panel

The final geometry should look like Figure 3.15 (p. 53).



Figure 3.15 The Final Geometry

f. Check the definition of the modeling objects to ensure that you specified them properly.

View → Summary (HTML)

Note

The HTML version of the summary displays in your web browser. The summary

displays a list of all the objects in the model and all the parameters that have been

set for each object. You can view the detailed version of the summary by clicking

the appropriate object names or property specifications. If you notice any incorrect

specifications, you can return to the appropriate modeling object panel and change

the settings in the same way that you originally entered them.

3.6. Step 3: Create Assemblies

For both organizational purposes and to have a finer mesh in the fan and enclosure, we will create two

assemblies. The first assembly will consist of the RF amplifier and heat sink; the second assembly will

consist only of the fan.



Step 3: Create Assemblies

1. To create the amplifier assembly:

a. Select the positive X view by either using the icon in the shortcut menu or simply press Shift+X

and then Shift+S to fit to scale the view in the graphics window.

b. While pressing Shift, drag a bounding box around the amplifier using the left mouse button. Re-

lease the mouse button and notice that all of the objects forming the amplifier and heat sink

have been selected in the model tree.

c. Right-click on the highlighted enclosure (Housing) in the model tree and select Create and then

Assembly from the list. All of the selected objects have now been added to the assembly.

d. In the Object geometry window, rename the assembly “assembly.1" to amplifier and click

Apply.

2. Create a new assembly for the fan object:

a. Click on the Create assemblies icon ( ) in the model toolbar to create a new assembly.

b. In the Model tree, use the left mouse button to drag the fan, delta.FFB0812_24EHE , into the

new assembly to add it to this assembly.

c. In the Object geometry window, rename this assembly as fan and click Apply.



Figure 3.16 Two Assemblies


Before generating a mesh, we will specify the slack values for the assemblies. Slack values represent a

finite offset from an object to a non-conformal mesh boundary and are required when meshing assem-

blies separately.

1. Edit both assemblies (right-click the assembly name in the model toolbar and select Edit), then select

the Meshing tab.




2. Toggle on Mesh separately and then specify the slack values indicated in the following table. Make

sure you remember to add slack values to both assemblies.

Table 3.1 Slack Values for the Amplifier and Fan

Max ZMax YMax XMin ZMin YMin XName

0.010.0500.010.020Amplifier

0.010.050.010.0100.01Fan

Figure 3.17 Fan Assemblies Panel

3. To create the mesh, go to Model → Generate Mesh. The Mesh control panel (Figure 3.18 (p. 57))

appears. The Mesh control panel can also be opened by clicking on the Generate mesh icon ( ) in

the shortcut menu.



Figure 3.18 The Mesh control Panel

4. As a first step, generate a coarse mesh by choosing Coarse in the Mesh parameters drop-down list

in the Global tab, as shown in Figure 3.18 (p. 57). Click Generate to create a mesh.

Note

If you have unchecked Allow minimum gap changes in the Misc tab, the Minimum

separation warning will appear. This warning message appears when the minimum

gap specified is more than 10% of the smallest sized object in the model. Please select

Change value and mesh if the warning message pops up.

5. To view the mesh, display a plane-cut view through the center of the cabinet, perpendicular to the

fins (y-z plane).

6. To create a plane-cut, follow these steps:

a. Click on the Display tab at the top of the Mesh control panel.

b. Toggle on Display mesh and Cut plane.

c. Under Plane location, set position to X plane through center in the drop-down list.

d. Press Shift+X to orient to the positive X direction and view the newly created plane cut.

e. Move the plane using the slider bar to see different views.

Make sure that the amplifier assembly is expanded and inspect the cells adjacent to the heat sink

fins. Notice that the resolution is coarse (Figure 3.19 (p. 58)), with only a couple of cells between

fins. As flow passes between the fins, boundary layers will grow and their degree of resolution




will dictate the accuracy of the simulation. It is advisable to have at least three to four cells between

fins to adequately resolve the growth of boundary layers. Better resolution is achieved by refining

the mesh.

7. Choose Normal in the Mesh parameters drop-down list in the Settings tab. Click Generate and inspect

the resulting mesh. Note that the number of cells between adjacent fins have increased (Figure

3.19 (p. 58)), providing better resolution of the boundary layers.

You can display the mesh on selected objects or the cut plane by using the context menu in the

graphics display window. To display the context menu, hold down the Shift key and press the

right mouse button anywhere in the graphics display window. Select Display mesh or Display

cut plane mesh in the context menu and the mesh will be displayed on selected objects or the

cut plane will be displayed.

It is also a good practice to select the Quality tab and review the Face Alignment, Quality,

Volume, and Skewness. The histograms show the figure of merit (Face Alignment, Quality Ratio,

Volume or Skewness) versus number of cells. By clicking on the bars that form the histogram, the

particular cells with that value of quality are displayed in the graphics window.

Figure 3.19 Coarse and Fine Mesh

8. Once you have explored the mesh quality, click Close to dismiss the Mesh control dialog box.


Before starting the solver, you will first review estimates of the Reynolds and Peclet numbers to check

that the proper flow regime is being modeled.

1. Check the values of the Reynolds and Peclet numbers.




a. Click the Reset button.

b. Check the values printed to the Message window.

The Reynolds and Peclet numbers are approximately 56282.6 and 39876.6 respectively, so

the flow is turbulent. ANSYS Icepak recommends setting the flow regime to turbulent.

Note

These values are only estimates, based on the current model setup. Actual values

may vary, and may need to be verified, depending on your design.

c. Click Accept to save the solver settings.

2. Enable turbulence modeling.


a. In the Basic parameters panel, select Turbulent as the Flow regime and keep the default Zero

equation turbulence model.

b. Turn on the Gravity vector option and make sure that gravity in the y-direction is -9.8 m/ ��

Note

Specifying gravity is important for the natural convection inside the RF amplifier.

c. Turn off radiation.

d. Click Accept to save the new setting.

The panel appears as shown in Figure 3.20 (p. 60).




Figure 3.20 Basic parameters Panel

3. Return to the Basic settings panel, specify the number of iterations as 300, click Reset and then Accept

again.

4. Set up the temperature limits for all the sources.

Model → Power and temperature limits

a. Enter a new value of 60°C for Default temperature limit.

b. Click on All to default.

c. Click Apply and then click Accept to close the panel.

Note

The default temperature limit is used during postprocessing to identify components

that exceed their limits or components that are close to this limit. This value is

not used to solve the problem.




ANSYS Icepak will save the model for you automatically before it starts the calculation, but it is a good






Note

You can click the save button ( ) in the File commands toolbar.


1. Create monitors.

Note

It is good practice to monitor the solution progress for certain objects. Dragging the

object in the model tree and placing it in the Points folder can accomplish this.

a. Drag device.2 and cabinet_default_side_maxY into the Points folder.

b. Right mouse click on the cabinet_default_side_maxY in the Points folder.

c. Select Edit and deselect temperature and activate Velocity (Figure 3.21 (p. 61)).

d. Click Accept to accept the modifications and to dismiss the per-object's Modify point panel.

Figure 3.21 The Modify point Panel




2. Start the calculation.


Note

Alternatively, you can click on the Run solution icon ( ) in the model and solve

toolbar to display the Run solution panel.

a. Enable Write overview of results when finished in the Results tab.

b. Click on the Start solution button to start the solver. While iterating the solution, windows will

appear showing convergence history, Figure 3.22 (p. 62) and Figure 3.23 (p. 63).

Figure 3.22 Convergence Plot



Figure 3.23 Monitor Plot


Once the model has converged (Figure 3.22 (p. 62) and Figure 3.23 (p. 63)), ANSYS Icepak automatically

generates a solution overview report. This report contains detailed information, such as object-based

mass and volumetric flow rates, fan operating points, heat flows for objects with specified power, heat

flows for objects that communicate with the ambient, maximum temperatures, and overall balances.

Please carefully review the solution overview and note that the solution satisfies conservation of mass

and energy (scroll to the bottom of the report). Also note the fan operating point. The solution overview

is automatically saved and can be reopened from Report → Solution overview → Create.

1. Compare the object temperature values for all sources with the temperature limits assigned.

Post → Power and Temperature values

The Power and temperature limit setup window appears.

a. Click Show too hot.

The Power and Temperature limit setup show the default temperature limit and the resulting

maximum temperature value for each source next to them.

If an assembly is expanded in the model tree and if the resulting temperature of any object

exceeds the temperature limit specified, ANSYS Icepak shows all the critical objects in red

color.

b. Click Accept to close the dialog box.

2. Create object faces.

Note

Ensure that the amplifier and fan assemblies are expanded, so that the fins are visible.




a. Press Shift+Z to orient the view in the positive Z direction.

b. To create an object face, click the Object face icon ( ) in the shortcut toolbar.

c. In the Object drop down list, specify heatsink.1 as the object and click Accept.

d. Select Show contours and click the Parameters button (adjacent to show contours) to access

the Object face contours edit dialog box.

i. Select This object in the drop-box adjacent to Calculated to use the object-based range.

ii. Click Done to close the Object face contours panel.

e. Click Done to close the Object face panel.

Note

You can also create contours on heatsink.1 by selecting this object in the

Model manager window and click the right mouse button to display the context

menu. Select Create>Object face(s)>Separate and the Object face panel will

appear. The Object face panel is displayed for that particular object.

Figure 3.24 Object Face Panel

Note

Using the mouse, rotate the heat sink to examine the surface temperature distribution.

Notice that the location of the devices is clearly discernible on the bottom of the heat

sink. Also note that the devices get progressively hotter in the flow direction (Figure

3.25 (p. 65)).



Figure 3.25 Temperature Contours on the Face

Note

Notice that face.1 has now appeared in the model tree in the Post processing folder.

Right mouse click on face.1 and note that you can deactivate, edit, and delete it.

You can move face.1 into the Inactive folder to deactivate it. Face.1 can be either

deleted or reactivated by dragging it to Trash or to the Postprocessing folder, as well

as with the right mouse click dialog.

3. Create plane cuts.

a. To create a plane cut, click the Plane cut icon ( ) in the shortcut toolbar.

b. Select the Set position as Point and normal and select Show vectors, as shown in the panel

below. Enter PX, PY, and PZ, as well as NX, NY, and NZ according to Figure 3.26 (p. 66).




Figure 3.26 Plane Cut

c. Click the Parameters button adjacent to Show vectors.

d. Select Uniform in Display options group box and specify value as 5000. The Uniform option for

the velocity will put the vectors uniformly in the 5000 data points.

e. Select This object in the drop-box adjacent to Calculated and click Done to close the panel.

The vector plots are shown in the graphics window (Figure 3.27 (p. 67)).



Figure 3.27 Velocity Vectors on the Mid X Plane

Note

Examining the vector plot, we can see that the flow pattern is symmetric, with two

large recirculating zones adjacent to the fan. Zoom into the region directly in front of

the fan and notice that two smaller recirculating zones exist in front of the hub. These

local effects can be important when objects are close to the hub region.

Note

You can move a plane cut through a model by pressing the Shift key, holding down

the middle mouse button on the edge of a vector and dragging the plane cut through

the model in the graphics display window.

4. Create isosurfaces.

a. Click the Isosurface icon ( ) in the shortcut toolbar.




b. Specify Temperature as the Variable, input a Value of 55°C, and select Show contours and click

Parameters. In the Isosurface contours panel, select Smooth for Shading options and This

object in the drop-box adjacent to Calculated. Click Done.

c. Click Update in the Isosurface panel and notice that an isosurface has been placed around all of

the sources, indicating that they have temperatures in excess of 55°C (Figure 3.28 (p. 68)).

Figure 3.28 Isosurface of Temperature 55°C

d. Now, change the Variable to Speed and input a Value of 4. Click Update. Notice that the regions

with velocities in excess of 4 m/s are now displayed (Figure 3.29 (p. 69)).

e. Once you have examined the isosurface, delete or deactivate it using one of the previously de-

scribed methods.



Figure 3.29 Isosurface of Speed 4 m/s

5. Create variation plots.

a. Click the Variation plot icon ( ) in the shortcut toolbar.

Note

Before creating the variation plots, please ensure that the amplifier assembly is

expanded, so that the fins are visible. Next, press Shift+Z to orient the view in the

positive Z direction.

b. Within the variation plot dialog box, complete the following:

i. Specify the Variable as UY.

ii. Click the From screen button.

iii. Click the left mouse button on the center on the heat sink fins.

iv. Click Create.

c. An xy-plot of UY velocity versus z-coordinate should now be visible. Toggle on the Symbols

button and notice that the velocity profile across the solution domain is now represented with

dots at the postprocessing locations. Notice that ANSYS Icepak has created a line that is colored

locally according to the UY velocity magnitude.

d. Save the xy-plot.

i. Click the Save button at the bottom of the Variation of UY plot window.

ii. Enter a file name in the resulting Save curve dialog box.

iii. Click Save to save the file in the model folder.





In this tutorial, you have learned about the usage of enclosure, PCB, source and heat sink objects. The

use of ANSYS Icepak's fan library and search tool has been explained. Meshing of assemblies and post-

processing features in ANSYS Icepak were also explained.



Chapter 4: Use of Parameterization to Optimize Fan Location

4.1. Introduction

The purpose of this tutorial is to demonstrate the following ANSYS Icepak features with the help of a

small system level model.


• Use network blocks as one way of modeling packages.

• Specify contact resistance using side specifications of a block object.

• Define a variable as a parameter and solve the parametric trials.

• Specify fan curves.

• Use local coordinate systems.

• Generate a summary report for multiple solutions.

4.2. Prerequisites


miliar with the interface. If you are not, please review Sample Session in the Icepak User's Guide and the

tutorial "Finned Heat Sink" of this guide as some of the steps that were discussed in these tutorials will

not be repeated here.


The system level model consists of a series of IC chips on a PCB. A fan is used for forced convection

cooling of the power dissipating devices. A bonded fin extruded heat sink with eight 0.008 m thick fins

is attached to the IC chips. The fan flow rate is defined by a nonlinear fan curve. The system also consists

of a perforated thin grille. A study is carried out for the optimum location of the fan by using the

parameterization feature in ANSYS Icepak.



Figure 4.1 Schematic of the Geometry





3. Specify a name for your project (i.e., fan_locations) and click Create.


cabinet in the graphics window. This cabinet will be modified in the next section.


1. Resize the default cabinet.

The cabinet forms the boundary of your computational model. Press the isometric view icon ( )

for a 3D view. Select Cabinet in the Model manager window and enter the location values as

shown in the panel below. The geometry window can be found in the lower right hand corner

of the GUI.



Extra

The previous tutorial showed you how to enter these values in the Cabinet panel.

2. Create the Fan.

Click on the Create fans icon ( ) in the object toolbar next to the model tree to create a 2D

intake circular fan on one side of the cabinet. Change the plane to yz and enter the location values

shown in the geometry window below:

• Defining a parameter for multiple trials.

One of the objectives of this exercise is to parameterize the location of the fan. To create a

parametric variable in ANSYS Icepak, input a $ sign followed by the variable name. Thus, to

create the parametric variable “zc,” type $zc in the zC box in addition to the other location

values, and click Apply. When ANSYS Icepak asks you for an initial value of “zc", enter an initial

value of 0.1 , and click Done.

Figure 4.2 The Param value Panel

We will now set the physical properties that will define the fan behavior:

a. Edit the fan object and go to Properties tab.

b. In the Properties tab, retain the selection of Intake for Fan type and select Non-linear in the

Fan flow tab.

c. Enter the characteristic curve by clicking on the Edit button and selecting Text Editor in the drop-

down list in the Non-linear curve group box.




Figure 4.3 The Fans Panel (Properties Tab)

d. First change the units of the volume flow rate and pressure according to the units in

Table 4.1: Values for the Curve Specification Panel (p. 74) and enter the values in pairs with a space

between them in the Curve specification panel.

Table 4.1 Values for the Curve Specification Panel

Pressure (in_water)Volume Flow (CFM)

0.420

0.2820

0.240

0.1460

0.0480

0.090

e. Click Accept to close the form.

f. Select the Edit button again in the Non-linear curve group box and click on Graph Editor in the

drop-down list to view the fan curve (Figure 4.4 (p. 75) ).



Figure 4.4 The Fan Curve Panel

g. Click Done to close the Fan curve panel.

h. In the Properties tab, give the fan an RPM of 4000 in the Swirl tab, located next to the Fan flow

tab.

i. In the Properties tab, give the fan an Operating RPM of 2000 in the Options tab, located next

to the Swirl tab.

Note

The fan curve defined originally for RPM=4000 will be automatically scaled accord-

ing to the fan laws for the new operating RPM=2000. The swirl RPM(4000) can

also be used to compute the swirl factor.

j. Click Update and Done to close the fan window.

Now the model looks as shown in Figure 4.5 (p. 76).




Figure 4.5 Model with Fan

Extra

The shading of the fan object can be changed by changing the Shading option under

the Info tab to change the shading of just that object, or by leaving it as default and

changing the default shading option by going to View → Default shading to change

the shading of all objects that have default shading selected.

3. Set up a Grille.

a. Click on the Create grille icon ( ) for creating a new grille, set its plane to yz. Then, using the

morph faces option move the grille to the max-X face of the cabinet. Step by step instructions

on how to use the morph faces option is presented in the graphics display window after clicking

the icon ( ) or you can also resize the grille as shown in the panel:

b. We will now define properties for the grill by clicking the Properties tab.

Note

This is a 50% open perforated thin grille.

i. Under velocity loss coefficient, retain the default selection of Automatic.

ii. Specify a Free area ratio of 0.5 .



iii. Retain Perforated thin vent for the Resistance type.

iv. Click Update and then Done to close the panel.

For more details on loss coefficient data, please refer to Handbook of Hydraulic Resistance, by I. E.

Idelchick.

The model looks as shown in Figure 4.6 (p. 77).

Figure 4.6 Model with Fan and Grill

4. Set up a wall.

Note

The model includes a 0.01 m thick PCB that touches and covers the entire min-Y floor

of the cabinet. The PCB is exposed to the outside with a known heat flux of 20 W/m2.

In order to take in consideration the heat flux, we will use a wall object to simulate the

PCB.

a. Click on the Create walls icon ( ) to create a new wall. We will define the geometry and phys-

ical parameters for the wall object:

i. Make the plane xz.

ii. Use the morph faces icon ( ) from the model toolbar so that the wall object covers the

entire min-Y floor of the cabinet.

iii. Edit the Wall object and go to Properties tab.




iv. In the Material group box, set the Wall thickness to 0.01 m and the Solid material to FR-

4.

v. In the Thermal specification group box, specify a Heat flux of 20 W/m2.

vi. Click Update and then Done to close the panel.

After creating the wall, the model looks as shown in Figure 4.7 (p. 78).

Figure 4.7 Model with Wall Added

5. Create blocks.

In this step, we will create several types of blocks to represent different physics.

• Creation of Solid Blocks

Now, we will create four blocks that dissipate 5 W each and have a contact resistance of 0.005C/W on their bottom faces.

a. Create a new block ( ) , and retain the type as solid and geometry as Prism. Enter the location

values shown in the panel below:

b. Edit the block and specify the following in the Properties tab:



i. In the Surface specification group box, click on the Individual sides check box and click

Edit (Figure 4.8 (p. 79)).

A. Select MinY and toggle on Thermal properties and Resistance.

B. Under Thermal condition, retain the selection of Fixed heat and Total power of 0W.

C. Select Thermal resistance from the drop-down menu next to Resistance.

D. Set Thermal resistance to 0.005 C/W and click Accept.

E. Click Accept to close the panel.

Figure 4.8 The Individual side specification

ii. In the Thermal specification group box in the Properties tab, retain the selection of

default for Solid Material (you can also select Al-Extruded which is the default).

iii. Set Total Power to 5 W.

iv. Click Update and Done to close the panel.

c. Next, make three copies of this block with an X offset of 0.08 m.

Extra

The previous tutorial showed you how to make a copy of an object.




Figure 4.9 Creation of Solid Blocks

• Creation of Network blocks

Let us now create four IC chips in the form of network blocks. To create a network block, we

will create a Block object and change the block type to Network in the Properties tab. Each

network block will have junction-to-board, junction-to-case, and junction-to-sides thermal

resistances. The values of these resistances are known a priori.

a. Add a new block, and position it as shown in the panel below:

b. Edit the block to change the properties of this block;

– Ensure that the Block type is set to Network.

– Toggle on Star Network.

→ Enter the Network parameters as shown in Figure 4.10 (p. 81).



Figure 4.10 The Properties Panel

c. Now make three copies of this network block with an X offset of 0.08 m. This finishes the

creation of the network blocks.

• Creation of a Hollow Block

Note

Finally, to cut out a section of the cabinet from the computational domain, we can

create a hollow block. This represents a region that does not affect heat transfer,

but alters the flow patterns.

a. Create a new Block; make sure it is a hollow.

b. In the Geometry tab, create a new Local coord system.

c. Select Create new from the Local coord system: drop-down list.

d. Enter X offset = 0.1, Y offset = 0, Z offset = 0.

e. Click Accept. This is just to demonstrate the use of local coordinate system.

f. Further, size the block as follows:




6. Now we will create the detailed heat sink. The heat sink base acts as a heat spreader for all the chips.

a. Click on the Create heat sinks icon ( ) and edit it, entering its location and properties as shown

in the following table:

Table 4.2 Heatsink Properties

Geometry

xzPlane:

0.02/0.34xS/xE:

0.03/—yS/yE:

0.1/0.23zS/zE:

0.01 mBase height:

0.06 mOverall height:

Properties

DetailedType:

XFlow Direction:

Bonded finDetailed Fin type:

Fin setup

Count/thicknessFin spec:

8Count:

0.008 mThickness:

Flow/thermal data

defaultFin material:

Cu-PureBase material:

Interface

Click the Edit buttonFin bonding:

0.0002 mEffective thickness:

defaultSolid material:

b. Click Update and Done. This completes the model building process. The complete model should

look like that shown in Figure 4.11 (p. 83).



Figure 4.11 Final Model

4.6. Step 3: Creating Separately Meshed Assemblies

One of the key aspects of modeling is to use an adequate mesh for the model. We need to have a fine

mesh in the areas where temperature gradients are high or flow is turning. Having a too coarse of a

mesh will not give you accurate results and at the same time, too fine a mesh may lead to longer run

times. The best option is to explore the model carefully and look for opportunities to reduce mesh

counts in the areas where the gradients are not steep. Creating non-conformal assemblies gives required

accuracy along with reduced mesh count. Select set of objects to create assemblies. Also decide suitable

slack values for assembly bounding box. Your selection can be reviewed in the section below where

we will create non-conformal meshed assemblies.

We will now create two non-conformal meshed assemblies.

1. To create the first assembly, first highlight all the blocks (except the hollow block) and the heat sink

object in the model tree, then right-click on them and choose Create and then Assembly.

2. Right-click and select Rename from the menu. Rename the assembly, as Heatsink-packages-asy.

3. To build the “bounding box" for the assembly called Heatsink-packages-asy, double-click on it to

edit the assembly.

4. In the Meshing tab of the Assemblies panel, toggle on Mesh separately, and then set the Slack

parameters as the following:

Table 4.3 Slack Values for Heatsink-packages-asy Assembly

0.015 mMax X0.005 mMin X



Step 3: Creating Separately Meshed Assemblies

0.005 mMax Y0.005 mMin Y

0.005 mMax Z0.005 mMin Z

Note

• Note that for the Heatsink-packages-asy, we have set a bounding box that is 0.005 m

bigger than the assembly at five sides except Max X where the slack is defined higher

(0.015 m) to capture the wake region of the flow.

5. Click Update and Done to complete the bounding box specifications for the assembly.

Following the same procedure above, create one more assembly for the fan object (name it Fan-

asy). Use the following table to assign the Slack values for the Fan-asy assembly.

Table 4.4 Slack Values for Fan-asy Assembly

0.005 mMax X0 mMin X




To generate the mesh:

1. Open the Mesh control panel, keep the default values for the mesh settings and ensure that Mesh

assemblies separately is on.

2. Click Generate. You will get a warning about minimum separation if the Allow minimum gap changes

option is unchecked in the Misc tab.

Extra

This warning appears because the Minimum gap (separation) which is like a tolerance

setting for the mesher is larger than 10% of the smallest feature in the model. When

there are objects smaller than the mesher tolerance, those objects will not be meshed

correctly. To avoid this we use the change value and mesh option which modifies the

minimum gap to 10% of the smallest object. This option is used for this particular tu-

torial and may not be applicable all the time. As separation setting is a useful tool de-

signed to avoid unnecessary mesh due to inadvertent misalignments in the model

(without modifying the geometry), we may use other options suitable to the model.

3. Click on Change value and mesh.

4. Examine the mesh by taking plane cuts; examine Face alignment and Quality ratio.

5. Go to the Mesh control panel, click on the Display and Quality tabs to examine the mesh.

4.8. Step 5: Setting up the Multiple Trials

Before we start solving the model, we will set up the parametric trials for the fan location parameter

“zc".



1. Go to the Solve menu and select Define trials.

a. The Parameters and optimization panel pops up.

b. Toggle on Parametric trials in the Setup tab.

c. Select the Design variables tab and next to Discrete values, type 0.165 following 0.1, separated

by a space as shown in the Figure 4.12 (p. 85):

Figure 4.12 The Parameters and optimization Panel- Design variables tab

d. Click Apply.

Note

After the first trial has been completed, ANSYS Icepak has the options of starting the

following trial(s) from the default initial conditions specified in Problem setup panel,

or from the solution(s) of the trial run(s) that have completed.



Step 5: Setting up the Multiple Trials

For this model, next go to the Trials tab and ensure the Restart ID is blank for the 2nd trial as

shown in Figure 4.13 (p. 86). This instructs ANSYS Icepak to start the 2nd run from the default

initial conditions.

2. Click on Reset button and select Values to use the base names for trial naming.

Figure 4.13 The Parameters and optimization Panel- Trials tab

3. Click Done to close the Parameters and optimization panel.

4.9. Step 6: Creating Monitor Points

Create two monitor points by dragging and dropping (block.1 and grille.1) into the Points folder to

monitor the velocity in the grille and the temperature in one of the solid blocks. The variables to be

monitored can be easily changed by selecting them in the Monitor points panel.



Figure 4.14 The Modify point Panel

4.10. Step 7: Physical and Numerical Setting

Set up the basic problem parameters to solve the flow and energy equations, and use the Zero equation

turbulence model. Since natural convection is not involved, there is no need to turn on the Gravity

vector.




Step 7: Physical and Numerical Setting

Figure 4.15 The Basic parameters Panel


Enter 200 in the Number of iterations field in the Basic settings panel.

Figure 4.16 The Basic settings Panel


ANSYS Icepak saves the model for you automatically before it starts the calculation, but it is a good








Alternatively, click the save button ( ) in the file commands toolbar.


The Solve panel is used for single trials only; therefore, the solution can only be calculated from the

Parameters and optimization panel. Open the Parameters and optimization panel and click Run to

calculate a solution for both trials.

Figure 4.17 The Parameters and optimization Panel- Trials tab





Once the solutions are done, click on the Post menu and select Load solution ID. Select the solution

that corresponds to the first (parametric) run, i.e., zc = 0.1. If you want to view objects inside the assem-

blies, you can open all the model nodes by right mouse clicking Model in the Model manager window

and selecting Expand all. Use the various postprocessing features available in ANSYS Icepak to display

your solution. A description of how to generate plane cut and object face views can be found in Step

7: Examine the Results of the Finned Heat Sink tutorial. In particular, use the following views:

1. Plane cut panel to display the velocity vectors on a plane through the cabinet

Figure 4.18 Trial 1 Vector Plots at Constant Z Plane Cut



Figure 4.19 Trial 2 Vector Plots at Constant Z Plane Cut

Important

To view the 2nd parametric run, click on the Post menu and select Load solution

ID. Select the solution that corresponds to the second parametric run, i.e., zc =

0.165. The graphics display window updates automatically.

2. Object face panel to display temperature contours on wall.1 and on all blocks




Figure 4.20 Trial 1 Temperature Contours on Blocks and PCB (wall.1)

Figure 4.21 Trial 2 Temperature Contours on Blocks and PCB (wall.1)

3. Object face panel to display temperature contours on the faces of the PCB (wall.1) and on all blocks

4. Surface probe panel to display the temperature values at a particular point



Examine the solution sets of both runs. You will find that, in the second run, the maximum tem-

perature is lower than in the first run and that the network blocks are the hottest objects inside

the cabinet. The second trial has the fan located at zC= 0.165 which is closer to the heat sink

location. This increases the flow velocity over the heat sinks and thus increases the convective

heat transfer coefficient, which leads to more heat transfer from the fins (blocks) and thus reduces

the maximum temperature.

4.14. Step 11: Reports

1. Overview Report

At the end of the runs, ANSYS Icepak automatically displays an overview report because you se-

lected Write overview of results when finished in the Solve panel. This report has:

• fan operating point

• volume flow rate through the grille

• heat flow from the chips

• network junction temperatures

• heat flows for the wall and the grille.

Examine these results. Go to the Report menu and then select Solution overview and click on

View to display the desired overview report.

2. Summary Report

You can also create a single summary report containing the results of all the trial runs completed.

Go to the Solve menu and select Define report. In the Define summary report panel, under ID

pattern, enter the default filter, "*", which picks all the available solution IDs. Press new and hold

down Ctrl and select block.1 , block.1.1 ., block.2 , block.2.1 , and block.3 from the

drop-down menu under Objects, and then press Write. Verify that the second trial gives lower

temperatures.


In this tutorial, you learned how to set up and solve parametric trials, specify fan curves and create a

new local coordinate system. The use of network blocks to model packages has been demonstrated as

well as how to specify contact resistance using side specifications of a block object. You also learned

how to generate a summary report for multiple solutions.

4.16. Step 13: Additional Exercise to Model Higher Altitude Effect

The final model can also be used to model the effects of higher altitudes. In order to model this correctly,

new air properties at the particular altitude need to be defined and assigned to the default fluid. The

density of air is the most affected property and gets lower as you go higher in altitude. The data for

air properties at a different altitude is presented in many handbooks and may even include temperature

change affect with it. For an altitude of 3000 m, we can select the available library material Air@3000m.

Please note that a custom material having any properties can be created and stored in the material

library to use in any project.



Step 13: Additional Exercise to Model Higher Altitude Effect

Then, select Problem setup → Basic Parameters and assign the new air material to the default fluid.

In addition, in the Fan flow section of the Fans Properties tab, all the defined fan curves need to be

modified by multiplying the existing data with the ratio of densities (the density of air at 3000 m / the

density of air at 0 m), which in this case is smaller than 1. Finally, the model is ready to be run to account

for the effects of higher altitude.





Step 13: Additional Exercise to Model Higher Altitude Effect

Chapter 5: Cold-Plate Model with Non-Conformal Meshing

5.1. Introduction

This tutorial demonstrates how to model a cold-plate using ANSYS Icepak.


• Use the priorities of different objects to model complex shapes in ANSYS Icepak.

• Use multiple fluids in a model.

5.2. Prerequisites

This tutorial assumes that you have reviewed Sample Session in the Icepak User's Guide and Tutorials

"Finned Heat Sink" and "RF Amplifier" of this guide.


The model consists of a cold-plate, where the cold-plate fluid is transporting a significant fraction of

the heat from two plates mounted on either side of it. The natural convection in the external air is also

instrumental in some heat transfer. The model setup is shown in Figure 5.1 (p. 101).

The objective of this exercise is to illustrate the use of two different fluids in ANSYS Icepak. The model

includes two heated plates, cooled by water circulating inside the cold-plate cavity, as well as by air

driven by natural convection externally. Separately meshed assemblies will be employed to reduce the

overall mesh count in the domain. The model will be constructed using the default metric unit system.


Create a new project called cold-plate.


Construct the cabinet and all the other objects according to the following specifications. Note that

during the model building, you may use the alignment tools. Please remember that you can align the

face, edge and vertex of one object with another. For example, you could align the bottom face of the

cylinders to the cabinet (see Figure 5.1 (p. 101)). You may also use the align tools to create the openings

on the cold-plate inlet and outlet regions.

• Cabinet

Enter the following start and end locations for the cabinet

Table 5.1 Cabinet Start and End Values

0.4 mxE0.0 mxS



0.3 myE0.0 myS

0.2 mzE0.0 mzS

• Blocks

Create a solid block, block.1, and a fluid block, block.2 with the following specifications. The table

below also gives the geometrical region where block.2 is located to have the material properties

of the fluid.

Table 5.2 block.1 and block.2 Specifications

0.35 mxE0.05 mxSblock.1

0.22 myE0.08 mySGeometry: Prism

0.13 mzE0.07 mzSBlock type: Solid

Solid material: Al-Extruded

0.34 mxE0.06 mxSblock.2

0.21 myE0.09 mySGeometry: Prism

0.12 mzE0.08 mzSBlock type: Fluid

Fluid material: Water (@280K)

Because block.2 is being created after block.1, it will have a higher relative meshing priority.

Note

Because Al-Extruded is set as the Default solid in the Defaults tab of the Basic para-

meters panel, you can then leave the material selection as default while creating the

object instead of selecting the material each time when an object is being created.

Next, we will create some cylindrical blocks. While editing cylindrical blocks, first select the block

shape as cylinder, then select the desired plane and finally enter the dimensions.

Table 5.3 Cylindrical Block Specifications

SpecificationsIRadiusRadiusHeightzCyCxCObject

Block type: Solid0.0 m0.015

m

0.09 m0.1

m

0.0

m

0.1

m

block.3

Solid material: Al-ExtrudedGeometry:

Cylinder

Plane: X-Z

Block type:Solid0.0 m0.015

m

0.09 m0.1

m

0.0

m

0.3

m

block.4

Solid material: Al-ExtrudedGeometry:

Cylinder

Plane: X-Z

Block type: Fluid0.0 m0.01 m0.09 m0.1

m

0.0

m

0.1

m

block.5



SpecificationsIRadiusRadiusHeightzCyCxCObject

Fluid material: Water(@280K)Geometry:

Cylinder

Plane: X-Z

Block type: Fluid0.0 m0.01 m0.09 m0.1

m

0.0

m

0.3

m

block.6

Fluid Material: Water(@280K)Geometry:

Cylinder

Plane: X-Z

Because the fluid blocks, block.5 and block.6, are created after the solid blocks, they will have

higher relative meshing priorities.

Note

An alternative way to build the cylinders would be to create the solid block, block.3,

and then the fluid block, block.5, group these together, and then copy them with an

offset of 0.2 in the x direction. Note that the naming of the cylinders will not be consistent

with the tutorial. However, you could rename the objects to their corresponding names

in the tutorial by right mouse clicking each copied object in the Model tree and selecting

Rename.

• Plates

Table 5.4 Plate Specifications

SpecificationsObject

Solid material:0.33 mxE0.07 mxSplate.1

Al-Extruded0.2 myE0.1 mySGeometry: Rectangular

Power: 200W—zE0.06 mzSPlane: X-Y

Thermal model: Conducting thick: 0.01 m

Solid material:0.33 mxE0.07 mxSplate.2

Al-Extruded0.2 myE0.1 mySGeometry: Rectangular

Power: 200W—zE0.13 mzSPlane: X-Y

Thermal model: Conducting thick: 0.01 m

Note

Note: An alternative way to create plate.2 would be to copy plate.1 with a Z offset of

0.07m.

• Openings




The openings at the liquid inflow and outflow regions of the cold-plate are

Table 5.5 Opening Specifications

SpecificationsRadiuszCyCxCObject

0.01 m0.1 m0 m0.1 mopening.1 (outlet opening)

Type: Free

Geometry: Circular

Plane: X-Z

Y velocity = 0.2 m/s0.01 m0.1 m0 m0.3 mopening.2 (inlet opening)

Type: Free

Geometry: Circular

Plane: X-Z

Note

You could also have made a copy of outlet opening (opening.1) with an X offset of

0.2 to create inlet opening (opening.2).

The openings at the cabinet boundary for external air natural convection are

Table 5.6 Openings at Cabinet Boundary Specifications

Object

—xE0.4 mxSopening.3

0.3 myE0.0 mySType: Free

0.0 mzE0.2 mzSGeometry: Rectangular

Plane:Y-Z

—xE0.0 mxSopening.4

0.3 myE0.0 mySType: Free

0.0 mzE0.2 mzSGeometry: Rectangular

Plane:Y-Z

Note

Instead of creating the openings, opening.3 and opening.4 above, you could have

edited the cabinet and changed the wall type on these two faces to openings.

The final model should appear similar to the drawing shown in Figure 5.1 (p. 101).



Figure 5.1 The cold-plate Model

Note

Figure 5.1 (p. 101) has changed the opacity, shading and color of some objects to make

the objects easier to see.

5.6. Step 3: Create a Separately Meshed Assembly

To create a separately meshed assembly, highlight all the objects in the model tree other than the

cabinet, opening.3, and opening.4. Right mouse click on them and choose Create and then Assembly.

To enable separate meshing for the assembly, double-click on assembly.1 to edit the assembly. Under

the Meshing tab, toggle on the Mesh separately button and then enter the slack values as follows:

Table 5.7 Slack Values for Mesh Assembly




The bounding box of the assembly is larger than the original assembly by 0.01 m on five sides. The

slack value for the min Y side of the assembly is set to be 0 m, since the min Y side of the assembly is

at the bottom surface of the cabinet. Click Update and Done to complete editing the separately meshed

assembly.



Step 3: Create a Separately Meshed Assembly


Open the Mesh control panel, make sure that the Mesh assemblies separately option is toggled on

and Normal mesh is selected for Mesh parameters. Change the Max size ratio to 4 and keep the

other global default mesh settings. The mesh needs to be refined for the inner prismatic fluid block

(block.2). In the Misc tab, make sure Allow minimum gap changes is checked. Then toggle on Object

params and click Edit in the Local tab. Choose block.2 and check Use per-object parameters and

enter 30, 16, and 10 respectively for the X, Y and Z counts for the mesh in the fluid block, as shown in

the following figure. Click Done to close the Per-object meshing parameters panel.

Click Generate to mesh the model. Visualize the mesh at plane cuts and surface displays from the

Display tab.




A calculation of the Reynolds number shows that the problem is turbulent. To set up turbulent flow,

go to Problem setup → Basic parameters and choose the Zero equation turbulence model

for the Flow regime in the General setup tab.

Gravity acts in the negative x direction in this problem. To setup the effects of gravity, toggle on the

Gravity vector in the General setup tab. Enter the new values for the gravity vector as x = -9.80665,

y = 0 and z = 0. Now go to the Transient setup tab and set an initial X velocity of 0.005 m/s in the x

direction. Accept all other defaults in the Basic parameters panel. These are shown in Figure 5.2 (p. 103).

Figure 5.2 Switching on Gravity and Turbulent Flow

Note

For steady state natural convection cases, setting a small initial velocity opposite to the

gravity vector direction is advised as this assists with the initial convergence of the model.

For cases where there is no forced convection, clicking on Reset in the Solution settings

→ Basic settings menu automatically sets a small initial velocity in the direction opposite

to the gravity vector. This may not be necessary in this model though, because the flow will

be forced through the cold plate. We will have mixed convection (forced + natural) heat

transfer mode.




Figure 5.3 Basic and Advanced Solver Settings

Select the Basic settings panel from the Solution settings branch of the tree and set the Number of

iterations to 300. Go to Advanced settings and make sure Under-relaxation factors for Pressure,

Momentum, and Temperature are 0.3, 0.7, and 1.0, respectively. Change the Stabilization under Joule

heating potential to BCGSTAB, and select Double for the Precision drop-down list. The recommended

basic settings and advanced solver setup for this model are shown in Figure 5.3 (p. 104).

Add three monitor points to the Points folder, one to monitor the velocity at the center of the opening.1

(outlet opening), and two to monitor the temperature at the center of block.2 and plate.2, respectively.

The easiest way to create them is to select the objects from the Model tree and then drag them to the

Points folder of the tree. ANSYS Icepak will then automatically monitor values at the centers of these

objects. The default setting is to monitor Temperature. To change this, double click on the object under

the Points folder, and choose which variables to monitor at that location.





idea to save the model after the model building and meshing is complete.


Alternatively, click the save button ( ) in the file commands toolbar.


Select the Solve menu and click on Run solution. In the Solve panel, under the Results tab toggle on

Write overview of results when finished, and then click Start solution.


Please review the solution overview report created to ensure that mass (volume) flow rate and energy

balances are satisfied. To postprocess the results, create the following object face and plane cut objects:

Table 5.8 Object Face and Plane Cut Specifications

DescriptionSpecifications/Display AttributesObject

Object-face view of temperature on all the blocks.

What is the maximum temperature?

Object: all blocks (select the blocks using

the Ctrl key or the Shift key and the left

mouse button)

face.1

Show contours/Parameters

Contours of: Temperature

Contours options: Solid fill and

Smooth

Color levels: Calculated/Global limits

Observation: Water is circulating through the internal

channel, providing most of the cooling for the

Set position: Z plane through centercut.1

Show vectors/ Parametersmodel. On the outside, air flows over the system by

natural convection.Color by: Velocity Magnitude

Color levels: Calculated/Global limits

Observe the flow pattern from inlet opening to

outlet opening passing through the cold plate. An-

imate the particle traces.

Objects: opening.1 (outlet) and open-

ing.2 (inlet)

face.2

Show particle traces/ Parameters

Variable: Speed

Display options: Uniform: 30

Particle options: Keep all the defaults

Style: Dye trace (Width = 1) and

Particles (Radius = 2)

Color levels: Calculated/ This Object

Observe the flow pattern in (+) X direction. Animate

the particle traces.

Set position: X plane through centercut.2

Show particle traces/ Parameters




Variable: Speed

Display options: Uniform: 30

Particle options: Keep all the defaults

Style: Dye trace (Width = 1) and

Particles (Radius = 2)

Color levels: Calculated/ This Object

Due to the nature of the problem, the temperature

distribution should be symmetric around the central

xy plane. Please verify this in the solution.

Set position: Y plane through centercut.3

Show contours of Temperature.

You can save the postprocessing objects that you just created by clicking Save post objects to file

option in the Post menu. ANSYS Icepak will save these objects under the file named post_objects in

the Icepak project folder. If you do not save them at this stage, they will not be automatically saved for

future retrieval when you end the current ANSYS Icepak session.


In this problem, we modeled a cold-plate that included two heat plates cooled by water circulating inside

the cold-plate cavity as well as air driven by natural convection externally. This exercise also demonstrated

how to use the priorities of different objects to model complex shapes in ANSYS Icepak and the use of

multiple fluids in a model.


To see the cooling capacity (effectiveness) of water, you may run the same model by replacing the fluid

properties (of the fluid blocks) by Glycol, i.e., make all the fluid blocks air blocks. You should see a sig-

nificant increase in the maximum temperature.



Chapter 6: Heat-Pipe Modeling and Nested Non-Conformal Meshing

6.1. Introduction

This tutorial demonstrates how to model simple heat pipes and an active heat sink using ANSYS Icepak.

In this tutorial, you will learn how to:

• Create orthotropic solid materials.

• Use those materials to simulate a heat-pipe in a system.

• Use of copy mirror and copy translate functions.

• Create nested non-conformal assemblies.

6.2. Prerequisites


miliar with the interface. If you are not, please review Sample Session in the Icepak User's Guide and the

tutorial "Finned Heat Sink" of this guide. Some steps in the setup and solution procedure will not be

shown explicitly.


Heat pipes are used to transport heat from a heat source area (where there is limited space for heat

dissipation) to a place where it is dissipated. The objective of this exercise is not to model the detailed

physics inside a heat pipe. Instead, we will model a heat pipe by using a series of cylindrical solid blocks

that connect the heat source to an air-cooled heat sink. These blocks will have an orthotropic conduct-

ivity with very large conductivity in the pipe axis direction where the heat is carried away. The model

will be constructed using the default metric unit system. We will also make use of nested non-conformal

meshing using assemblies to reduce the cell count in the model.



Figure 6.1 Heat-pipe Tutorial Base Model


1. Copy the file ICEPAK_ROOT/tutorials/heat-pipe/heat-pipe-nested-NC.tzr to your

working directory. You must replace by the full path name of the directory where ANSYS Icepak is in-

stalled on your computer system.


Note

ANSYS Icepak can be started in ANSYS Workbench using the import .tzr feature or it

can be opened as a stand-alone product.



3. Click Unpack in the Welcome to Icepak panel.

4. In the File selection panel, select the packed project file heat-pipe-nested-NC.tzr and click

Open.

5. In the Location for the unpacked project file selection dialog, select a directory where you would

like to place the packed project file, enter a project name in the New project text field then click Un-

pack.


Note

In ANSYS Icepak, the packed file feature compresses a model to the files needed to build,

mesh and run the model (job, model and problem files). In many of the tutorials, part of the

model is already created and packed to speed up the learning process. The model originally

has three blocks and only block.1 has an assigned power (25 W). The model also has one

fan and one grille. Next, we will build a heat sink in the area of the fan, grille and the heat

pipe system to connect block.1 to the heat sink.

1. Create materials utilizing ANSYS Icepak's orthotropic material conductivity feature. The idea is to have

a material that has very high conductivity in the pipe heat removal directions but normal conductivity

in the other directions.

• Click on the material icon ( ) in the object toolbar for each new material to be created.

• Click on the material name with the right mouse button and select Edit or double click the mater-

ial name to open the Edit panel.

• Go to the Properties tab and make sure to toggle on Material type to be Solid and set the Con-

ductivity type to be Orthotropic from the drop-down list.

• Deselect the Edit check box next to conductivity and create the following materials with ortho-

tropic conductivity properties using the template in Figure 6.2 (p. 110).




Figure 6.2 Orthotropic Material Properties

Table 6.1 Orthotropic Properties

Orthotropic multiplierNominal ConductivityName

Z = 0.005Y = 0.005X = 120000material.1

Z = 0.005Y = 1X = 0.00520000material.2

Z = 0.005Y = 1X = 120000material.3

The above materials have the so-called orthotropic conductivity, which is not uniform in all

three directions. The effective conductivity in each direction is equal to the Nominal conduct-

ivity multiplied by the orthotropic multiplier in that direction.

2. After creating these heat pipe materials, we build the heat pipe made of cylindrical blocks and square

joints.

• Create five block objects.

• Use the values in the following table (be sure to note the geometry)

Table 6.2 Block Specifications

SpecificationsIRadiusRadiusHeightzCyCxCGeo-

metry

Object

Type: Solid0.0 m0.01 m0.245

m

0.1

m

0.11

m

0.05

m

Shape:

Cylin-

der

pipe1

Solid material:

material.1

Plane:

Y-Z



SpecificationsIRadiusRadiusHeightzCyCxCGeo-

metry

Object


m

0.1

m

0.365

m

0.325

m

Shape:

Cylin-

der

pipe2

Solid material:

material.1

Plane:

Y-Z


m

0.1

m

0.125

m

0.31

m

Shape:

Cylin-

der

pipe3

Solid material:

material.2

Plane:

X-Z

SpecificationszEyExEzSySxSGeo-

metry

Object

Type: Solid0.115 m0.125

m

0.325

m

0.085

m

0.095

m

0.295

m

Shape:

Prism

Joint1

Solid material:

material.3

Type: Solid0.115 m0.38 m0.325

m

0.085

m

0.35

m

0.295

m

Shape:

Prism

Joint2

Solid material:

material.3

Note

You can use the Copy object function to speed up the creation of the remaining

objects after pipe1 and joint1 are created. However, the names will not be the

same as the tutorial. To rename an object, right mouse click the object in the

Model tree and click Rename.

3. Next, we will also build the heat sink using block objects.

• Build the base and one pin according to the following

Table 6.3 Base and Pin Specifications

PropertieszEyExEzSySxSGeo-

metry

Ob-

ject

Block type: Solid0.15 m0.38 m0.592

m

0.05

m

0.35

m

0.42

m

Shape:

Prism

Base

Solid material:

default

PropertiesInt radi-

us / Int

radius 2

Radius

/ Radi-

us 2

HeightzCyCxCGeo-

metry

Ob-

ject

Block type: Solid0 m / 0

m

0.01 m /

0.006 m

0.04 m0.067

m

0.38

m

0.44

m

Shape:

Cylinder,

Pin




Solid material:

default

Plane: X-

Z

Non-uni-

form radi-

us

Note that the non-uniform radius option is in the Geometry tab as shown below and that the

Plane option is X-Z (Figure 6.3 (p. 112)).

Figure 6.3 Non-uniform Cylinder

• Make two copies of Pin with an offset of 0.033 m in the Z direction (i.e., Number of copies= 2,

Translate with Z offset = 0.033 m).

• Highlight the three tapered fins (Pin, Pin.1 and Pin.2), make four copies of this highlighted group

with an offset of 0.033 m in the X direction (i.e., Number of copies = 4, Translate with X offset

= 0.033 m).



• Group all the pins by highlighting them in the model tree, click on the right mouse and select

Copy and finally make one copy as follows: Number of copies = 1, Translate with Y offset = -0.03,

Mirror with Plane: XZ and About: Low end.

The final model should appear as shown in Figure 6.4 (p. 113).

Figure 6.4 Model with Heat Pipe and Heat Sink

6.6. Step 3: Create Nested Non-conformal Mesh Using Assemblies

In this exercise, our goal is to reduce the overall cell count to a reasonable level while retaining a good

cell resolution within the model, especially where the velocity and temperature gradients are higher.

1. Create three individual assemblies (one for the heat sink and the base, the second one for the vent,

and the last one for the fan).



Step 3: Create Nested Non-conformal Mesh Using Assemblies

a. Highlight all the pins and the base in the model tree.

b. Right mouse click and select Create then Assembly.

c. Rename the assembly as Heatsink-asy.

d. Double click on the assembly to open the Edit panel.

e. Under the Meshing tab, toggle on the Mesh separately button.

f. Set the slack to the following values:

Table 6.4 Slack Values for Heatsink-asy




Note

For the Heatsink-asy, we have set a bounding box that is 0.005 m bigger than

the assembly at five sides except Min Z where the slack is defined higher (0.015m)

to capture the wake region of the flow.

g. Click Update and Done.

h. Following the same procedure above, create two more assemblies; one for vent.1 (name it Vent-

asy) and one for the fan (name it Fan-asy).

i. Use the following tables to assign slack values for Vent-asy and Fan-asy assemblies, respectively.

Table 6.5 Slack Values for Vent-asy



0 mMax Z0.01 mMin Z

Table 6.6 Slack Values for Fan-asy



0.01 mMax Z0 mMin Z

2. Put the previously created assemblies into an outer assembly covering all.

a. Highlight all the three assemblies above and click the right mouse button.

b. Select Create assembly.

c. Rename this main assembly HS-vent-fan-asy.

d. Assign the following slack values to the assembly.

Table 6.7 Slack Values for HS-vent-fan-asy





0 mMax Z0 mMin Z


1. Go to Model → Generate Mesh or use the toolbar shortcut ( ) to open the Mesh control panel.

2. In the Mesh control panel, specify a global maximum element size of 0.025 m in all three directions

(Max X size = Max Y size = Max Z size = 0.025).

3. Verify that the Coarse option is selected next to Mesh parameters and change the Max size ratio

from 10 to 5.

4. Make sure that Mesh assemblies separately button is toggled on.

5. Under the Options tab, set the Init element height to 0.003.

6. Click Generate. Visualize the mesh by making plane cuts and surface displays under the Display tab,

especially between the heat sink pins and on the surface of the fan and grille objects. The meshing

panel should look like the one in Figure 6.5 (p. 115) when finished:

Figure 6.5 Mesh control Panel


1. Go to Problem setup → Basic parameters. In the General setup tab, change the Flow regime

to be Turbulent and keep the default selection of Zero equation.




2. Go to the Transient setup tab and set the initial condition for the velocity in the z-direction to be

-0.1 m/s to achieve faster convergence (If there is an initial guess at the start of the solution there

is a lesser chance of large initial velocities in the first iteration).

These two steps are shown in Figure 6.6 (p. 116). Click Accept for these changes to take effect.

Figure 6.6 Turbulent Flow and Initial Z-Velocity

3. Under Solution settings → Basic settings, set the Number of iterations to 200 (Figure

6.7 (p. 116)).

Figure 6.7 Basic settings Panel

4. Click Accept.



idea to save the model (including the mesh) yourself as well.





1. Add in two monitor points, one to monitor velocity at the center of vent.1, and one to monitor the

temperature at the center of the block.1.

a. Select vent.1 and block.1 from the list and then drag them to the Points branch of the tree.

(Alternatively, one can create monitor points by simply selecting these objects in the model tree,

clicking on the right mouse button and selecting Create and then Monitor point.)

b. Because ANSYS Icepak will by default monitor the temperature at the centroid or center of these

objects, double-click on vent.1 under the monitor Points branch.

c. Select velocity as the variable to monitor and deselect temperature.

d. Accept the change.

2. Go to Solve → Run solution or click on the shortcut button ( ). Start the solver by clicking Start

solution.


To postprocess results for this exercise, create the following object-face and plane-cut views:


DescriptionSpecificationsOb-

ject

Object-face view of temperature on all the blocks.

Observations: The view shows the flow of heat

from the heated block (block1.) to the air-cooled

heat sink.

Object: all blocks

(Choose using Ctrl and Shift keys

and left mouse button)

face.1

Show contours

Parameters


Contours options: Solid fill/ Smooth

Color levels: Calculated/ Global limits

Plane cut (x-z) view of the velocity vectors through

the center of the fan.

Observations: The view shows air flowing from

the grill to the fan, passing through the fins of

the heat sink.

Plane location:cut.1

Set position: Y plane through center

Scroll up to about 0.8

Show vectors

Parameters

Color by: Velocity magnitude

face.1 and cut.1 should look similar to Figure 6.8 (p. 118) and Figure 6.9 (p. 119) that follow.




Figure 6.8 face.1 (Temperature Contour -all blocks)



Figure 6.9 cut.1 (Velocity Vectors through Fan)


In this problem, we have modeled a simplified heat pipe using cylindrical solid blocks of orthotropic

conductivity. The exercise also demonstrated the application of copy and mirror features as well as the

use of nested non-conformal meshing using assemblies in ANSYS Icepak.



Step 9: Summary

Chapter 7: Non-Conformal Mesh

7.1. Introduction

This tutorial compares the effects of using a conformal mesh versus a non-conformal mesh in a simple

pin-fin heat sink problem.


• Generate a non-conformal mesh and related parameters such as bounding box, slacks etc.

• Understand the effects of non-conformal mesh on total mesh counts and on results.

• Generate and compare summary reports.

• Apply non-conformal rules and restrictions.

7.2. Prerequisites

This tutorial assumes that you are familiar with the menu structure in ANSYS Icepak and that you have

solved Sample Session in the Icepak User's Guide and the tutorial "Finned Heat Sink". Some steps in the

setup and solution procedure will not be shown explicitly.


The model consists of a pin-fin heat sink composed of aluminum, which is in contact with a source

dissipating 10 W, as shown in Figure 7.1 (p. 122). The source-heatsink assembly sits in the middle of a

wind tunnel with a wind speed of 1.0 m/s. The ambient temperature is 20°C. The flow regime is turbulent.

The objective of this exercise is to become familiar with the non-conformal meshing methodology and

its application. The solution results of conformal and non-conformal mesh will be examined and com-

pared.

In ANSYS Icepak, assemblies of objects can be meshed separately. A region can be defined around a

particular assembly and this region can be meshed independently of the mesh outside this region. This

allows a fine mesh to be confined in a particular region of interest and it helps to reduce overall mesh

count without sacrificing the accuracy of the results.





Open a new project and name it non-conformal.


• Cabinet

Enter the following start and end locations for the Cabinet.

0.7 mxE0.3 mxS

0.7 myE0.5 myS

1.0 mzE0.0 mzS

– Opening on Cabinet Boundaries

Open the Cabinet object panel. In the Properties tab, change Wall type of Min z to Opening.

Click Edit to open the Openings panel. In the Properties tab of the Openings panel, enter 1

m/s for the Z velocity and keep Temperature as ambient (which is 20°C).

– Grille on Cabinet Boundaries

Under the Properties tab of the Cabinet panel, change the wall type of Max z to Grille. Click

Edit to open the Grille panel. In the Properties tab of the Grille panel, change the free area

ratio to 0.8 and leave the other default property specifications.



Figure 7.2 Grille Properties Specifications

• Source

Create a source using the following dimensions:

SpecificationObject

Total power: 30 WxE = 0.52 mxS = 0.48 msource.1

yE = —yS = 0.52 mGeometry: Rectangular

zE = 0.52 mzS = 0.48 mPlane: X-Z

• Heat sink

Now, create a heat sink with the following geometrical and physical properties.

SettingsTab

Plane: X-ZGeometry

Start/end

xS = 0.46 m, xE = 0.54 m

yS = 0.50 m, yE = —

zS = 0.40 m, zE = 0.6 m

Base height: 0.02 m

Overall height: 0.1 m

Type: DetailedProperties

Flow direction: Z




Detailed fin type: Cross cut extrusion

Fin setup/Fin spec: Count/thickness

Count: 8 in Z-dir and 8 in X-dir

Thickness: 0.01 m in Z-dir and 0.004 m in X-dir

Flow/thermal data: default base and pin material

The screen shots of the heatsink panel is shown in Figure 7.3 (p. 124).

Figure 7.3 Heat sink Properties

7.6. Step 3: Generate a Conformal Mesh

Generate a conformal mesh for the model.

1. Open the Mesh control panel using Model → Generate mesh.

a. In the Mesh control panel, set the Max element size for X to 0.02 m, for Y to 0.01 m, and for

Z to 0.05 m.

b. Under the Global tab, make sure that Normal is selected next to Mesh parameters.

c. Under the Misc tab, make sure Allow minimum gap changes is checked.

d. Click Generate.

Note

The minimum gap for X, Y, Z might adjust to 10% of the minimum dimension in

respective directions. Make a note of the number of elements, the minimum face

alignment and the aspect ratio.

2. Examine the mesh.





c. In the Set position drop-down list, select Y plane through center.


Note

The mesh display plane is an x-z plane cut through the center of the cabinet as shown

in Figure 7.4 (p. 125). Note the clustered mesh lines extending from the heat sink all the

way across the domain in both the x and z directions. The total number of cells is about

144000.

Figure 7.4 Conformal Mesh, Central Y Plane


a. Deselect the Display mesh option.

b. Click Close to close the Mesh control panel.


Before starting the solver, you first review estimates of the Reynolds and Peclet numbers to check that

the proper flow regime is being modeled.





Click Reset in the Basic settings panel. Check the values printed to the Message window. The Reynolds

and Peclet numbers are approximately 12600 and 8900, respectively, so the flow is turbulent.

To set up turbulent flow, go to Problem setup → Basic parameters and choose the Zero

equation turbulence model under the General setup tab. Click Accept to accept the new solver settings.

Go to Solution settings → Basic settings and set the Number of iterations to 300. Go to Ad-

vanced settings and specify Under-relaxation factors for Pressure, Momentum, and Temperature

as 0.7, 0.3, and 1.0 respectively.

Define a monitor point by dragging the source object (source.1) into the Points folder. This creates a

monitor point for temperature of the object, which can be used to judge convergence.



idea to save the model (including the mesh) before the solution. The model can be saved using File

→ Save project.


Start the calculation by clicking on Solve → Run solution. Specify “conformal" as the ID. Click Start

solution to start the solver.


In this step, you will examine the maximum temperature using ANSYS Icepak's summary reporting tool.

Report → Summary report

1. Define a report that will display temperature data for the source and the heat sink.

a. In the Define summary report panel, click New.

b. In the Objects drop-down list, select heatsink.1 and click Accept.

c. In the Value drop-down list, select Temperature.

d. Repeat steps (a) through (c) for source.1.



e. Click Write to generate a summary report.

ANSYS Icepak opens the Report summary data panel, where minimum, maximum, and mean

temperatures for the heat sink and source are displayed. Note that the maximum temperature is

about 36.7° C.

2. Click Done to close the Report summary data panel.

3. Click Close to close the Define summary report panel.

7.11. Step 8: Add an Assembly to the Model

You will now create an assembly out of the source and heat sink objects. The assembly will be meshed

separately from the rest of the model.

Note

Because you are changing the current model, thereby invalidating the post-processing data

that has been loaded from the previous steps, you will need to generate a mesh (a non-

conformal mesh) and calculate the solution again which is shown in steps 9 through 11.



Step 8: Add an Assembly to the Model

1. Create an assembly consisting of the source and the heat sink objects.

a. Click the Create assemblies button ( ) to create a new assembly. This creates an assembly node

in the Model manager window under the Model node.

b. Select the source.1 item under the Model node in the Model manager window, hold down the

Ctrl key, and then select the heatsink.1 item.

c. Hold down the left mouse button, drag both highlighted items into the assembly.1 node of the

tree, then release the left mouse button.

2. Edit the assembly and define its bounding box.

a. Select the assembly.1 node in the Model tree, and then click the Edit object button ( ) to open

the Assemblies panel.

b. Click the Meshing tab.

c. Turn on the Mesh separately option and enter the Slack parameters shown in Figure 7.5 (p. 128).

Figure 7.5 Slack Values and Mesh Controls in the Separately Mesh Assembly

This creates a bounding box region that is 0.05 m larger than the assembly on four sides.

Since Min Y is already at the bottom of the cabinet, no slack value can be provided for it. A

larger slack value of 0.15 m has been provided in the Max Z direction to resolve the wake

region. Not that a smaller Max X and Max Z grid size has been specified within the assembly

compared to the global max grid size. This helps to refine the mesh within the separately

meshed assembly.



d. Click Done to set the properties of the assembly and close the panel.

The new model is shown in Figure 7.6 (p. 129).

Figure 7.6 The Source and Heat Sink in a Separately Meshed Assembly

7.12. Step 9: Generate a Non-conformal Mesh

assembly.1 will be meshed separately when the mesh is generated. The non-conformal mesh will limit

the clustering to a region inside a bounding box slightly larger than the source-heatsink assembly.

1. Generate a non-conformal mesh for the model.


a. In the Mesh control panel, keep the Max element size for X set to 0.02 m, for Y set to 0.01m, and for Z set to 0.05 m.

b. Under the Global tab, make sure the Mesh assemblies separately option is checked.

c. Click Generate to create the mesh.

Note

Make a note of the number of elements, the minimum face alignment, and the

aspect ratio.




Step 9: Generate a Non-conformal Mesh





The mesh display plane is an �- � plane cut through the center of the cabinet as shown in

Figure 7.7 (p. 130). Note the clustered mesh lines extending from the heat sink all the way

across the domain in both the � and � directions only within the bounds of the assembly.

The total number of cells is about 107000.

Figure 7.7 Non-conformal Mesh


a. Deselect the Display mesh option.

b. Click Close to close the Mesh control panel.






1. Retain the same Number of iterations (300 ) in the Basic settings panel.



2. Start the Solution.


a. Specify non-conformal as the solution ID.

b. Click Start solution to start the solver.

Note

The monitor point that you already created is automatically used for the new solution.

The solution converges after about 175 iterations. Note, however, that the exact number of itera-

tions required for convergence may vary on different computers.


In this step, you will examine the maximum and minimum temperatures of the source and heat sink in

the new version of the model.

Report → Summary report

1. Define a report that displays temperature data for the assembly.

a. Retain the same temperature report of the source and the heat sink, as used in the version without

the assembly.

b. Click Write to generate a summary report.

Note that the maximum temperature is about 35.8° C, representing a temperature rise of

about 15.8° C from the ambient temperature of 20° C. The maximum temperature is very

close to that obtained in the version with conformal mesh.

2. Click Done to close the Report summary data panel.

3. Click Close to close the Define summary report panel.


In this tutorial, you generated both a conformal and a non-conformal mesh for a simple source-heatsink

geometry and compared the two sets of results. The comparison found an approximate 20 percent re-

duction in the number of cells for the non-conformal mesh with a negligible change in the temperature

data.



Step 13: Summary

Chapter 8: Mesh and Model Enhancement Exercise

8.1. Objective

The objective of this exercise is to lead you through the decision making process that's involved in

improving a model. The inferences from the exercise should help you make appropriate modeling

choices during your next thermal modeling project.

8.2. Prerequisites

The trainee should be familiar with:

• ANSYS Icepak modeling objects

• Basics of meshing

• Non-conformal meshing

8.3. Skills Covered

• Choice of thin vs. thick objects

• Basic meshing techniques


• Use of object separation setting

8.4. Training Method Used

A troubleshooting approach is used in this tutorial. A model with potential for improvement is provided.

You will be given 15 minutes to try your hand at improving the model (note: you are not expected to

complete all the improvements in this short time). This will help you familiarize yourself with the issues

associated with the model. Then, an approach for improving the model is delineated in the form of

step-by-step hints. Feel free to explore the software interface, collaborate with another trainee, or ask

the instructor.

8.5. Loading the Model

• Unpack and load the model named meshing-tutorial-start.tzr .

• Rename it to any other name of your choice.

8.6. A 15 Minute Exploration

Without making any changes, the model results in about 750,000 cells. It is possible to reduce this mesh

significantly without compromising accuracy. You are allowed to modify, delete, or add objects as long

as the physics being modeled stays unchanged. You may want to refer to the power and material spe-

cifications to justify model changes. Non-conformal meshing is one of the techniques that will help you

accomplish this task.



Work with this model for as long as you prefer within the allocated 15 minutes and STOP. Proceed to

the next set of instructions.

Hint

Start by generating the mesh without any changes. View mesh cut planes at various orient-

ations and locations to identify root causes that result in unnecessary mesh clusters in non-

critical regions. Then modify the model in order to tackle the issues you notice.

8.7. Step-by-Step Approach

• Save the model you have been working on to another name. (You may be revisiting this model to

compare notes with the suggested approach)

• Reload the model you had unpacked earlier (“meshing-tutorial-start").

• Save it to another name of your choice.

• Generate mesh without modifying the model. You will see a mesh count of about 750,000 cells.

Note

Ensure the meshing type is Mesher-HD.

• Create mesh cut planes in different orientations to identify the root cause for such a high mesh count.

One such cut plane (Z plane through center set position) is shown in Figure 8.1 (p. 135).

• Figure 8.1 (p. 135) shows that the high mesh count is due to grid bleeding from the heat sink and the

components cooled by it.

Note

What feature in ANSYS Icepak allows you to avoid grid bleeding?



Figure 8.1 A Mesh Cut Plane View of the Given Model When Meshed Without

Modifications

8.8. Modification 1: Non-Conformal Mesh of the Heat Sink and Compon-

ents

1. Create an assembly containing the heat sink and the components cooled by it (green colored objects).

Name it HS-asy.



Modification 1: Non-Conformal Mesh of the Heat Sink and Components

Tip

• Shift + left mouse click and draw a window around the group of objects you would like

to assemble.

• You can make the mesh and some objects invisible to select the heat sink objects.

• You can also select the objects in the Model manager window by left mouse clicking

heatsink.1 and then Shift + left mouse clicking HS_component.

2. We will test two non-conformal assembly options: a regular non-conformal assembly (with slack values)

and a zero slack non-conformal assembly.

Regular non-conformal assembly

a. Activate Mesh separately under the Meshing tab of the Assemblies panel for this assembly (HS-

asy) and specify appropriate slack values (we recommend 1 mm on all sides). While specifying

slack values, make sure that you are not violating any of the rules regarding non-conformal

meshing.

Note

It is recommended to use the Case check macro to ensure a thin conducting plate

is not intersecting a non-conformal assembly. In the Macros menu, select Case

check> Automatic Case Check Tool. Click the Apply button for the following

options: Assembly intersection check and Thin Conducting Plate and Assembly

Intersections. If there is an intersecting plate, the slack value should be changed

to get rid of this error.

b. Generate the mesh again.

c. Observe the decrease in element count with every modification you make. The mesh count should

be around 315,000 cells.

Zero slack non-conformal assembly

a. Open the HS-asy edit panel and change the slack values on all sides to zero.

b. Generate the mesh again.

c. Display the mesh at some selected planes to observe mesh in the domain.

d. Display the mesh on Mask.1. Note that the mesh fully exists for the plate, even though it is inter-

secting with a face of the assembly.

e. Observe the reduction in the mesh count; the mesh count should be about 260,000 cells.

Note

Zero slack non-conformal assembly resulted in fewer mesh count than the regular non-

conformal assembly intersecting thin conducting plate. This limitation will be resolved

in the next step.



8.9. Modification 2: Resolution of Thin Conducting Plate Intersecting

Non-Conformal Region

• Question the choice of using the thin conducting plate object type for the plate object (Mask.1).

– What is the thickness of the mask plate?

– What is the conductivity of the solid material assigned to this plate?

– Find out the thickness and conductivity of the PCB on which the thin plate is lying.

– Based on the above information, do you think that the mask object is a significant spreader of heat

compared to the PCB?

→ The mask is not a significant heat spreader, however it tends to impede heat flow across it.

Hence, we cannot completely ignore it.

→ In fact, there are two mask plates modeled as thin conducting plates in this model (one for each

PCB).

→ Change the plate type of both mask plates to Contact Resistance while maintaining the same

thickness (0.00001 m). This way you maintain the thermal resistance in the normal direction while

ignoring the heat spreading laterally.

• Regenerate the mesh or load the existing one (the mesh is still the same as there is no change in geo-

metry).

• View cut planes of the mesh to see if you have any more unnecessary mesh clusters. Figure 8.2 (p. 137)

shows one such cut plane.

– This time the unwanted grids are from the clusters of components called “hi-flux-comp" (red colored

objects).

Figure 8.2 Mesh Bleeding After 1 Non-Conformal Region

8.10. Modification 3: Non-Conformal Mesh for the hi-flux-comps Cluster

1. Create a non-conformal mesh around the cluster of components called “hi-flux-comps".



Modification 3: Non-Conformal Mesh for the hi-flux-comps Cluster

Even though you are only interested in isolating the “hi-flux-comps ", there are two cylindrical

objects very close to it. You have two choices.

• Avoid the cylinders by using zero slack value. This may be too small and create a small gap between

the interface and the cylinders, which is not desirable.

• Include the cylinders to the assembly. This is the suggested approach.

2. Create a zero slack non-conformal assembly that includes the hi-flux-comps , Tabs , Dies , and

adjacent cylinders . Note that the Tabs and Dies are contained within the hi-flux-comps .

3. Generate the mesh again.

4. Repeat cut plane viewing. Figure 8.3 (p. 138) shows a cut plane view after creating the two separate

mesh regions.

Figure 8.3 Mesh Bleeding from the Boards

8.11. Modification 4: A Super Assembly...

• The mesh bleeding you see in Figure 8.3 (p. 138) can be tackled by creating a separately meshed assembly

of the entire enclosure object (the blue box). In order to see the effect of zero slack non-conformal as-

semblies, you may want to try meshing the model once with zero slack assembly, and then with slack

values for the non-conformal assembly.

• The resultant mesh cut plane is shown in Figure 8.4 (p. 139).



Figure 8.4 Cut Plane View of Recursive Embedded Mesh

• This method of creating a super assembly containing sub-non-conformal assemblies is called “nested

non-conformal meshing" or “recursive embedded meshing".

• Revisiting the Separation Setting

By default, ANSYS Icepak's accepts all minimum gap changes. We shall revisit these changes now.

– In the Mesh control panel, set all the Minimum gap settings to 0.0001 m.

– In the Misc tab, uncheck Allow minimum gap changes.

– Generate the mesh.

– The pop-up message as shown in Figure 8.5 (p. 139) will appear.

Figure 8.5 Separation Warning

– This warning appears because the separation (think of it as a tolerance setting for the mesher) distance

is larger than 10% of the smallest feature in the model.

– When there are objects smaller than the mesher tolerance, those objects will not be meshed correctly.

– However, note that the separation setting is a useful tool designed to avoid unnecessary meshes

due to inadvertent misalignments in the model (without modifying the geometry).

– Look for the name of the object featured in the warning and its dimension.

– Why should you model an object that's 0.1 mm in thickness? Is it likely to improve the accuracy of

your results?



Modification 4: A Super Assembly...

– Do not accept the suggested change to the separation settings.

8.12. Modification 5: A Simplification Based on Magnitudes of Resist-

ances...

• From the name of the object, one can infer that the warning is regarding an air gap under one of the

components, which is modeled as a thick plate.

• There is a reason for not using contact resistance type plate to model the Airgap.

– Two thin objects cannot overlap. If the Airgap was modeled as contact resistance plate, the under-

lying mask may not be meshed in the region common to the Mask and the Airgap.

→ What is the Mask thickness and conductivity?

→ What is the Airgap thickness and conductivity?

→ The purpose for modeling these two objects is to capture their insulating effects.

→ How does the resistance (thickness/conductivity) of the mask compare to that of the Airgap?

→ Does the mask contribute significantly to the overall (sum) of the two resistances?

→ Can you justify suppressing the mask under the air gap by making the Airgap a contact resistance

plate?

→ When you make the Airgap a contact resistance plate, make sure that the Effective thickness

is the same (1e-4 m).

→ Also make sure the Airgap has higher priority over the Mask object.

• You can do this by editing the plate object and changing the Priority setting under the Info

tab. (Larger priority number means higher priority. Objects with higher priority are listed

lower in the Model manager window).

• Generate the mesh again.

• This time you will see another separation warning about the AL-spreader. Again, do not accept the

changes.

8.13. Modification 6: A Classic Case for Thin Conducting Plate...

• Since a contact resistance plate will not model the in-plane spreading of heat, we can't use it here.

Thin conducting plate models conduction in the normal as well as the planar direction. At the same

time the thin conducting plate will not generate slender cells.

The decrease in thickness due to a thin plate approximation of the Al-spreader is negligible.

• Generate the mesh one more time. You will see the separation warning again - this time about the die

objects which are 0.0004 m.

– These objects are power generating components, which are already thin conducting plates. The

warning is about the width of the packages.

– The surface area of the dies is a critical parameter affecting the temperature prediction for the

component. This cannot be simplified.

– Hence accept the suggested change in separation setting. The resultant mesh count will be signific-

antly less than what we got without any changes to the given model.



Note

It is also possible to use a separation distance larger than the recommended 10% value.

Values of up to 50% (of the smallest dimension) may be used in cases where reducing

the mesh count is critical.

• You will now get a separation warning about the tabs. We cannot change the geometry of the tabs, so

accept the suggested change in separation settings again.

• Here are some suggested qualities of meshes:

– The size of the first cells from critical heat dissipating surfaces should be less than 1 mm for a 1st

cut analysis.

→ View mesh cut plane on the wall of the enclosure object, the PCB and the critical heat generating

components to see if you are fulfilling the above requirement.

→ Use the Object params control to request mesh refinement near all the important surfaces

mentioned above.

– Generate the mesh to see if your request is being honored.

• Finally, a comparison...

For comparison purposes, deactivate the Mesh assemblies separately option in the Mesh control

panel and generate the mesh. The difference between the mesh with this check button active and

inactive is the effect of non-conformal meshing.

• STOP: Solution and post processing are beyond the scope of this exercise. Please compare the suggested

approach with the approach you were attempting during the initial 15 minute period of this tutorial.

8.14. Conclusion

A model with room for improvement is provided. Using approximate object choices and meshing

strategies, the model and the mesh were improved. The approach delineated in this exercise can help

reduce significant run time without compromising the physics being modeled.



Conclusion

Chapter 9: Loss Coefficient for a Hexa-Grille

9.1. Introduction

This tutorial demonstrates how to define trials, run parametric solutions, and post-process the results.

Often, there is a need to calculate the loss coefficient of grilles that have certain hole patterns. The

purpose of the problem is to determine the minor loss coefficient of a grille that has hexagonal holes.


• Define a parameter to optimize the design.

• Define trials.

• Define primary and compound functions that you want to report.

• Calculate parametric solutions.

• Report and plot parametric results.

9.2. Prerequisites


solved or read the tutorial "Finned Heat Sink". Some steps in the setup and solution procedure will not

be shown explicitly.


The model includes a cabinet that is 160 mm in length with inlet and outlet openings at the two ends

(with cross sectional area of 7.363 mm x 12.7 mm), and four symmetry walls at the other sides. The

model also includes a part of the hexa-grille placed at the center of the channel in the streamwise dir-

ection, as shown in Figure 9.1 (p. 144). The grille has one full hexagonal hole at the center and four

quarter hexagonal holes placed around it. This pattern was selected because it forms a periodic region

and is sufficient to calculate the loss coefficient. The solution obtained from this run can be replicated

to form the solution for the entire domain.





1. Copy ICEPAK_ROOT/tutorials/loss-coefficient/loss-coefficient.tzr to your

working directory. Replace ICEPAK_ROOT by the full path name of the directory where ANSYS Icepak

is installed on your computer system.




The File selection panel appears.

4. In the File selection panel, select the packed project file loss-coefficient.tzr and click Open.

The Location for the unpacked project file selection dialog appears.


like to place the packed project file, enter a project name in the New project text field, then click

Unpack.


This tutorial uses an existing model. ANSYS Icepak displays the model in the graphics window, as shown

in Figure 9.2 (p. 145).



Figure 9.2 Loaded Model

Save the problem to a new project file.

This enables you to expand on the problem without affecting the original file.

File → Save project as

1. In the Project text box, enter the name loss-coefficient-new .

2. Click Save.




9.6. Step 3: Define Parameters and Trials

You will first define a parameter and trials according to the parameter. Next, you will define a summary

report, then primary and compound functions to be reported.

1. Define a velocity parameter at the inlet opening in terms of the Reynolds number (��).

Note

The velocity at the inlet opening in terms of the Reynolds number (��), which is cus-

tomarily used in loss-coefficient plots in lieu of velocity, is calculated as = ∗� �� ,

where the kinematic viscosity ν = 1.5843e-5 kg/m.s, and the hydraulic diameter of the

duct Dh = 9.322e-3 m.

a. Select the inlet opening, cabinet_default_side_minx, in the Model manager window, and then

click the Edit object button ( ) to open the Openings panel.

b. Click the Properties tab.

c. Select X Velocity and set the value to $Re*1.5843e-5/9.322e-3 .



d. Click Done to set the properties of the opening. This opens the Param value panel.

e. Set the Initial value of Re to 10 , and click Done to close both the Param value and the Openings

panels.

2. Define six trials according to the different values of the Reynolds number.

Solve → Define trials

a. In the Parameters and optimization panel, make sure Parametric trials and All combinations

are enabled in the Setup tab.

b. Click on the Design variables tab, enter the following values for the Reynolds number in the box

next to Discrete values: 10 50 100 500 1000 1750 .

Click Apply to accept the changes.



Step 3: Define Parameters and Trials

Note

Parameters values can also be exported/imported by clicking the Export or Import

button in the Setup tab of the Parameters and optimization panel. Clicking Ex-

port or Import opens a file selection dialog box and overrides any existing data.

c. Click the Trials tab to review the trials. Make sure the Trials across top option at the bottom of

the tab is disabled, and click Reset to select Values instead of Numbered in order to use the

base names as values.




d. Click Done to close the panel.

3. Define the report that displays average velocity and pressure data at the inlet and outlet openings.

Solve → Define report

Note

The loss coefficient is obtained by dividing the total pressure differential through the

domain by the average dynamic pressure, = −− −� � � ��

.

a. In the Define summary report panel, click New.

b. In the Objects drop-down list, select cabinet_default_side_maxx and click Accept.

c. In the Value drop-downlist, select UX.

d. Repeat steps (a) and (b), then select Pressure in the Value drop-down list.

e. Repeat steps (a) through (d) for cabinet_default_side_minx.



f. Click the Close button to accept the settings and close the panel.

4. Set the parametric trials and define primary and compound functions.

Solve → Run optimization

a. In the Parameters and optimization panel, click the Setup tab.

b. Verify that the Parametric trials and All combinations options are turned on.

c. Click the Functions tab.

d. Define four primary functions (Pstat_in , Pstat_out , Uave_in , and Uave_out ).

Note

These functions represent static pressures and velocities at the inlet and outlet,

respectively.

i. Under Primary functions, click the New button to open the Define primary function panel.

ii. In the Define primary function panel, enter Pstat_in for the Function name.

iii. Select Report summary from the Function type drop-down list and cabinet_de-

fault_side_minx Pressure from the Item drop-down list and retain the selection of Max.

iv. Click Accept to accept the changes and close the panel.




v. Repeat steps (i) through (iv) for the following three functions:

Max/MeanItemFunction typeFunction

name

Maxcabinet_de-fault_side_maxxPressure

Report summaryPstat_out

Meancabinet_de-fault_side_minx UX

Report summaryUave_in

Meancabinet_de-fault_side_maxx UX

Report summaryUave_out

Important

All function names are case-sensitive.

5. Define five compound functions (Pdyn_in , Pdyn_out , Ptot_in , Ptot_out , and Kfact ).

a. Under Compound functions, click the New button to open the Define compound function

panel.

b. In the Define compound function panel, enter Pdyn_in for the Function name.

c. Next to Definition enter 0.5*1.1614*$Uave_in*$Uave_in .

d. Click Accept to accept the changes and close the panel.

e. Repeat steps (a) through (d) for the following four functions:

DefinitionFunction name

0.5*1.1614*$Uave_out*$Uave_outPdyn_out



$Pstat_in+$Pdyn_inPtot_in

$Pstat_out+$Pdyn_outPtot_out

($Ptot_in-$Ptot_out)/$Pdyn_outKfact

6. Click Done to close the Parameters and optimization panel.


For this model, you will generate the mesh in just one step. The resulting mesh will be sufficiently fine

near object faces to resolve the flow physics properly.

Model → Generate Mesh

1. Generate the mesh for the model.

a. Keep all the defaults in the Mesh control panel.

b. Click Generate in the Mesh control panel to generate the mesh.









Note

The mesh display plane is an �- � plane cut through the center of the cabinet as

shown in Figure 9.3 (p. 154).

Figure 9.3 Mesh on the x-z Plane

3. Deselect the Display mesh option to turn off the mesh display.

4. Click Close to close the Mesh control panel.


1. Confirm that only the flow solution is to be obtained, and the flow regime is set to laminar.


a. Keep the default selection of Flow(velocity/pressure) under Variables solved.

b. Keep the default selection of Laminar for the Flow regime.

c. Click Accept to close the panel.

2. Increase the Number of iterations to 500 .


a. Enter 500 in the Number of iterations field.

b. Click Accept in the Basic settings panel.

3. Confirm under-relaxation factors are correct.

Solution settings → Advanced settings



The Advanced solver setup panel opens.

a. Confirm that the Under-relaxation factor for Pressure is 0.7 and for Momentum is 0.3 .

b. Click Accept in the Advanced solver setup panel.




the calculation, you will be able to open the project you saved and continue your analysis in a future

ANSYS Icepak session. (If you start the calculation in the current ANSYS Icepak session, ANSYS Icepak will

simply overwrite your project file when it saves the model.)



Start the calculation.

1. Solve → Run optimization

Note

Alternatively, you can click the button in the Model and solve toolbar to display

the Parameters and optimization panel.

2. Make sure Allow fast trials (single .cas file) is unchecked in the Setup tab.

3. Click Run in the Parameters and optimization panel.


As ANSYS Icepak starts performing the trials, the Parametric trials panel opens, displaying all the

function values defined a priori, as well as parameters and running times for each trial. The Parametric

trials can also be opened by selecting Show optimization/param results from the Report menu.

Report → Show optimization/param results

Plot the loss coefficient, Kfact, against the Reynolds number, Re.

1. In the Parametric trials panel, click the Plot button to open the Selection panel.




2. In the Selection panel, select Re as the � axis variable, and click Okay.

3. In another Selection panel, which automatically opens up, select Kfact as the y axis variable, and click

Accept.

This displays the plot Kfact vs Re, as shown in Figure 9.4 (p. 156)

Figure 9.4 Kfact vs Re Plot


In this tutorial, you used the parameterization tool to calculate the loss coefficient of a grille for different

values of Reynolds number (Re). You also defined other functions (e.g., static pressure and velocities at

the inlet and outlet) that were reported for different Reynolds numbers. The results show that as Re

increases, the loss coefficient decreases.



Chapter 10: Inline or Staggered Heat Sink

10.1. Introduction

This tutorial demonstrates how to use the check-box (boolean) parameter control for design variables,

and how to assign primary functions, in order to determine whether an inline or a staggered pin fin

heat sink performs better in a single model. The resulting maximum temperature on the package will

be compared. Non-conformal meshing will also be employed to reduce the cell count, required memory,

and run time. In addition, particle traces passing a non-conformally meshed assembly will be presented

during the post-processing of the results.


• Define a check-box parameter (design variable).

• Define different values for a design variable.

• Run and report parametric trials.

• Clip a plane cut to align it with the sides of a heat sink assembly.

• Display particle traces coming from the fan and the opening.

10.2. Prerequisites


solved or read Tutorial Finned Heat Sink (p. 3). Some steps in the setup and solution procedure will

not be shown explicitly.


The model includes the package assembly, containing a BGA package object (compact conduction

model), inline or staggered assemblies consisting of the respective heat sink objects, PCB object,

spreader plate, a fan at the exit, and an opening at the inlet of the wind tunnel. The model geometry

is shown in Figure 10.1 (p. 158).





1. Copy the file

ICEPAK_ROOT /tutorials/heat_sink/heat_sink2b.tzr to your working directory. You

must replace ICEPAK_ROOT by the full path name of the directory where ANSYS Icepak is installed

on your computer system.

2. Start ANSYS Icepak, as described in Section 1.5 of the User's Guide.

Note

When ANSYS Icepak starts, the Welcome to Icepak panel will open automatically.




Note

The File selection panel will appear.

4. In the File selection panel, select the packed project file heat-sink2b.tzr and click Open.

Note

The Location for the unpacked project file selection dialog will appear.



Unpack.


Note

This tutorial uses an existing model. ANSYS Icepak will display the heat sink model in the

graphics window. To view all components, expand all the assemblies of the model in the

Model manager window.

Note

You can rotate the cabinet around a central point using the left mouse button, or you can

translate it to any point on the screen using the middle mouse button. You can zoom into

and out from the cabinet using the right mouse button. To restore the cabinet to its default

orientation, select Home position from the Orient menu.

Save the problem to a new project file.

Note

This will allow you to expand on the problem without affecting the original file.


• In the Project name text box, enter the name heat-sink-new .

• Click Save.




10.6. Step 3: Define Design Variables

Note

For both heat sinks, you will define the HeatSink parameter, which will activate/deactivate

heat sinks parametrically.

1. Define the HeatSink parameter for the Inline heat sink.

a. Select the Inline assembly in the Model manager window, and then click the Edit object button

( ) to open the Assemblies panel.



b. Right-click the Active check box to open the Active parameter panel.

c. Select ON if variable is equal to this object's name.

d. Enter $HeatSink in the Variable text box.

Caution

Note that all function names are case sensitive.

e. Click Accept in the Active parameter panel to accept the changes and close the panel.

f. Click Update in the Assemblies panel to open the Param value panel.



Step 3: Define Design Variables

g. In the Param value panel, enter Staggered for the Initial value of HeatSink, and click Done

to close the panel.

Note

The word Active in the Assemblies panel became green. Also, note that the Inline

assembly in the Model manager window is moved to the Inactive node.

h. Click Done in the Assemblies panel to close the panel.

2. Define the HeatSink parameter for the Staggered heat sink.

a. Repeat above steps for the Staggered assembly.

Note

You will not have to specify the initial value again.

10.7. Step 4: Define Parametric Runs and Assign Primary Functions

You will first define values for your design variable. Next, you will review parametric trials and define

primary functions to be calculated and reported.


Extra

Alternatively, you can click the button.

1. Define parameter values.

a. In the Parameters and optimization panel, click the Design variables tab.

b. Next to Discrete values, after "Staggered" type in "Inline" . Make sure to separate the

two with a space.

c. Click Apply to accept the changes.



2. Review trials.

a. Click the Trials tab.

b. Make sure that the Order for Staggered is 1, and for Inline is 2.

c. Select tr_HeatSink_Staggered as the Restart ID for the tr_HeatSink_Inline trial as shown in the

image below.



Step 4: Define Parametric Runs and Assign Primary Functions

3. Define a primary function.

a. Click the Functions tab.

b. Click the New button in the Primary functions group box.



c. In the Define primary function panel, enter Tmax next to Function name.

d. In the Value drop-down list, select Maximum temperature of objects.

e. In the Object drop-down list, select the 700_BGA_40X40_5peripheral_p1.50 object in the

Package assembly, and click Accept.

f. In the Define primary function panel, click Accept to save the changes and close the panel.

g. Click Done in the Parameters and optimization panel to close the panel.


For this model, you will not generate a mesh in advance. Meshing will be automatically performed for

each design trial during the parametric trials.




Model → Generate Mesh

1. Make sure that the Mesh type is Hexa unstructured.

2. In the Global tab, make sure that the Mesh assemblies separately option is turned on.

3. Keep all other defaults in the Mesh control panel.

4. Click Close in the Mesh control panel to close the panel.


Define basic parameters.


• Set the Number of iterations to 300.

• Click Accept in the Basic settings panel to accept the settings and close the panel.








10.11. Step 8: Define Monitor Points

It is always a good approach to define monitor points before starting to run a simulation. In this model,

a temperature monitor point was already defined by dragging the BGA package object into the Points

node in the Model manager window. A velocity monitor point was also defined by dragging the Xmax

opening object into the Points node and selecting Velocity and unchecking Temperature from the

Modify points panel. In addition to the residual plot, the monitor plot will display temperature at the

center of the BGA package object during the solution process and provide an indication of convergence.


1. Open the Parameters and optimization panel, if it is not already opened.


Note

You can click the button in the Model and solve toolbar.

2. Click the Setup tab, and make sure that options Parametric trials and All combinations are selected.

Deselect Allow fast trials (single .cas file).

3. Click Run in the Parameters and optimization panel, to start the calculations.



Note

As ANSYS Icepak starts calculating solutions for the model, the Solution residuals

window, displaying convergence history, and the Temperature Point monitors window

will open. Also, the Parametric trials panel will open displaying the function values,

as well as parameters and running times for both trials, as shown in Figure 10.2 (p. 167).

The Parametric trials can also be opened by selecting Show optimization/param

results from the Report menu.

Figure 10.2 The Parametric trials Panel


The results from tr_HeatSink_Inline will be examined in this section.

1. In the Orient menu, select Orient negative Z.

2. Display velocity vectors on a plane cut at the exit region of the heat sink.

Post → Plane cut

Extra

You can also open the Plane cut panel by clicking the button.

a. In the Name field, enter the name cut_velocity .

b. In the Set position drop-down list, select Vertical - screen select.

c. Select a point in the graphics window between the fan and the heat sink assembly.

d. Turn on the Show vectors option, and click Parameters to open the Plane cut vectors panel.

e. In the Plane cut vectors panel, in the Color levels group box, select This object from the Calcu-

lated drop-down list.

f. Check Project to plane.




g. Click Done in the Plane cut vectors panel to accept the changes and close the panel.

h. In the Orient menu, select Isometric view.

Note

The graphics window will be updated, as shown in Figure 10.3 (p. 168)

Figure 10.3 Velocity Vectors at the Exit Region of the Heat Sink

3. Move this plane cut through the model.

a. Hold down the Shift key, press and hold down the middle mouse button on the edge of a vector.

b. Drag the plane cut through the model in the graphics display window.



4. Clip the plane cut to align it with the sides of the heat sink assembly.

a. In the Orient menu, first select Orient positive X, then Scale to fit.

b. Unexpand the Inline assembly node in the Model manager window if it was expanded in order

to see the edges of the assembly in the graphics window.

c. In the Plane cut panel (that was already opened), select Enable clipping, then click Max Y in the

orange region under Clip to box.

d. Click the top edge of the assembly in the graphics window.

e. In the Plane cut panel, click Min Z in the orange region under Clip to box.

f. Click the left edge of the assembly in the graphics window.

g. In the Plane cut panel, click Max Z in the orange region under Clip to box.

h. Click the right edge of the assembly in the graphics window.

i. Click the Update button.

Note

The graphics window will be updated, as shown in Figure 10.4 (p. 170)




Figure 10.4 Clipped Plane Cut

5. Display particle traces in a forward direction.

a. In the Orient menu, select Isometric view.

b. In the Plane cut panel, unselect Show vectors and Enable clipping and select Show particle

traces.

c. Click Parameters next to Show particle traces to open the Plane cut particles panel.

d. Select Speed from the Variable drop-down list.

e. In the Display options group box, keep the default selection of Uniform, and enter 50 .

f. In the Style group box, keep the default selection of Dye trace and select Particles with Radius

2.

g. In the Color levels group box, select This object from the Calculated drop-down list.

h. Click Done to update the graphics window.

Note

The graphics window will display the particle traces in the forward direction, as

shown in Figure 10.5 (p. 171)



Figure 10.5 Forward Particle Traces

6. Display particle traces at the opening (Xmax).

a. In the Orient menu, select Orient negative Z.

b. In the Plane cut panel, deselect Active and click New.

c. In the Name field, enter the name opening-velocity .

d. In the Set position drop-down list, select Vertical - screen select.

e. Select a point in the graphics window near the opening (Xmax). This point will should be around

0.814 on the slider bar.

f. Turn on the Show particle traces option, and click Parameters to open the Plane cut particles

panel.

g. Select Speed from the Variable drop-down list.

h. In the display options group box, keep the default selection of Uniform, and enter 50 .

i. In the Style group box, keep the default selection of Dye trace and select Particles with Radius

2.

j. In the Color levels group box, select This object from the Calculated drop-down list.

k. Click Done in the Plane cut particles and Plane cut panels to close the panels and update the

graphics window.

l. In the Orient menu, select Isometric view.




Figure 10.6 Opening particle traces


In this tutorial, you used the optimization tool to determine whether an inline or a staggered pin fin

heat sink performs better in a single model. The resulting maximum temperature on the package was

found to be higher in the case of the staggered heat sink.



Chapter 11: Minimizing Thermal Resistance

11.1. Introduction

Heat sink optimization is crucial in a variety of industrial applications. Usually, the challenge is to min-

imize the thermal resistance (or to maximize the heat transfer) and the amount of material used for the

heat sink. The objective of this tutorial is to minimize the thermal resistance for the big heat sink, while

keeping the maximum temperature in the entire system below 70°C and ensuring that the total mass

of the heat sinks does not exceed 0.326 kg.


• Set up an optimization problem.

• Define design variables.

• Define primary, compound, and objective functions.

11.2. Prerequisites





The model comprises an FR-4 board (FR-4.1) of 20.32 cm × 30.48 cm and 1.59 mm thick with several

components placed on the board (Figure 11.1 (p. 174)). Two grilles are placed at the upstream and

downstream of the board with the free flow area ratios of 60% and 50%, respectively. There are also

two components (block.1.3 and block.1.3.1) dissipating 5 W each.

There is a CPU (block.1) dissipating 50W and a heat sink (heatsink_small) is placed on the top of it.

Between the heat sink and the CPU, there is a thermal interface material (TIM_1) with a thermal con-

ductivity of W/mK. These components and three small power caps (power_cap_1.1, power_cap_1.1.1

and power_cap_1.1.2), dissipating 1 W each, form a non-conformal assembly (hs_assembly_1).

On the other side of the board, there are eight chips, dissipating 20 W each, and a parallel plate heat

sink (heatsink_big) is placed on the top of the chips. Similar to the case of the small heat sink, there

is a thermal interface material (TIM_2.1 and TIM_2.1.1) between the large heat sink and the chips with

the same thermal conductivity. These components together form a non-conformal assembly (hs_as-

sembly_2).





1. Copy ICEPAK_ROOT/tutorials/optimization/optimization.tzr to your working directory.

Replace ICEPAK_ROOT by the full path name of the directory where ANSYS Icepak is installed on

your computer system.





4. In the File selection panel, select the packed project file optimization.tzr and click Open.




Unpack.


This tutorial uses an existing model. ANSYS Icepak will display the model in the graphics window. To

view all components, expand all the assemblies of the model in the Model manager window.



Note

You can rotate the cabinet around a central point using the left mouse button, or you can

translate it to any point on the screen using the middle mouse button. You can zoom into

and out from the cabinet using the right mouse button. To restore the cabinet to its default

orientation, select Home position from the Orient menu.

Save the problem to a new project file (this enables you to expand on the problem without affecting

the original file).


1. In the Project name text box, enter the name optimization-new .

2. Click Save.

11.6. Step 3: Define Design Variables

The large heat sink needs to be optimized in terms of the number of fins and fin thickness. Therefore,

you will define the following design variables for the large heat sink: fin count (in the range from 2 to

18) and fin thickness (in the range from 0.254 mm to 2.032 mm).

1. Define the finCount and finThick design variables for the heatsink_big and specify their initial

values.

a. Expand the hs_assembly_2 node in the Model manager window.

b. Select the heatsink_big in the Model manager window and click the Edit object button ( )

to open the Heat sinks panel.

c. Click the Properties tab.

d. Under the Fin setup tab, type $finCount next to Count, and press Enter on the keyboard to

open the Param value panel.

Important

All function names are case-sensitive.

e. In the Param value panel, enter 12 for the Initial value of finCount, and click Done to close the

panel.

f. In the Heat sinks panel, under the Fin setup tab, type $finThick next to Thickness, and press

Enter on the keyboard to open the Param value panel.

g. In the Param value panel, enter 0.762 for the Initial value of finThick, and click Done to close

the panel.



Step 3: Define Design Variables

h. Click Done in the Heat sinks panel to close the panel.

2. Specify the constraint values for the design variables.


Extra

Alternatively, you can click the button.

a. Turn on the Optimization option in the Setup tab. Then click on the Design variables tab.



The design variables that you had defined will be listed in the panel, and their initial values

will be shown in the Base value text box.

b. Select finCount from the list, then enter 2 for the Min value constraint, 18 for the Max value

constraint.

c. Select Allow only multiples, keep the default value of 1, and click Apply.

d. Select finThick from the list, then enter 0.254 for the Min value constraint, 2.032 for the Max

value constraint, and click Apply.

e. Make sure Allow only multiples is only activated for finCount, not finThick.

f. Click Done to close the Parameters and optimization panel.


For this model, you will not generate a mesh in advance. Meshing will be automatically performed for

each design trial during parametric trials.

Model → Generate Mesh.

1. Make sure that the Mesh type is Mesher-HD and the Mesh assemblies separately option is turned

on.

2. Make sure the Allow minimum gap changes is enabled in the Misc tab.

3. Click Close in the Mesh control panel to close the panel.






1. Keep all the defaults in the Basic parameters panel.

2. Click Accept in the Basic parameters panel to accept the settings and close the panel.

Solution settings → Basic Settings

1. Make sure Number of iterations is 125.

2. Make sure the convergence criteria for Flow is 0.001, and for Energy is 1e-7.

3. Click Accept to close the Basic settings panel.







11.10. Step 7: Define Primary, Compound, and Objective Functions

Note

The objective of this tutorial is to minimize the thermal resistance of the heat sink while

keeping the maximum temperature for the entire system below 70°C and ensuring that the

total mass of the heat sinks does not exceed 0.326 kg. Therefore, you will define the following

primary functions: thermal resistance for the large heat sink (bighsrth ), mass of the large

heat sink (bighsms ), mass of the small heat sink (smlhsms ), and global maximum temper-

ature of 70°C (mxtmp). You will also define a compound function, the total mass of the heat

sinks of 0.326 kg (totalmass ). For the objective function, you will minimize the thermal

resistance of the large heat sink (bighsrth ).

1. Go to Solve → Run optimization to open the Parameters and optimization panel.

2. In the Functions tab, define four primary functions.

a. Define the thermal resistance function for the large heat sink (bighsrth ).

i. Click the New button under Primary functions.



ii. In the Define primary function panel, enter bighsrth next to Function name.

iii. In the Function type drop-down list, keep the default selection of Global value.

iv. In the Value drop-down list, select Thermal resistance of heatsink.

v. In the Object drop-down list, select the heatsink_big object under hs_assembly_2, and

click Accept.

vi. In the Define primary function panel, click Accept to save the changes and close the panel.

b. Define the mass function for the large heat sink (bighsms ).

i. Repeat step (a) for the bighsms as the Function name, Global value as the Function type,

Mass of objects as the Value, and heatsink_big as the Object.

c. Define the mass function for the small heat sink (smlhsms ).

i. Repeat step (a) for the smlhsms as the Function name, Global value as the Function type,

Mass of objects as the Value, and heatsink_small as the Object.

d. Define a constraint function as the global maximum temperature of 70°C (mxtmp).

i. Click the New button under Primary functions.

ii. In the Define primary function panel, enter mxtmp next to Function name.

iii. In the Function type drop-down list, keep the default selection of Global value.

iv. In the Value drop-down list, keep the default selection of Global maximum temperature.

v. Select Constraint and keep the default selection of Max value.

vi. Enter 70 in the text entry field and click Accept to save the changes and close the panel.

3. Define a compound function.

a. Under Compound functions, click the New button to open the Define compound function

panel.

b. In the Define compound function panel, enter totalmass for the Function name.

c. Next to Definition enter $bighsms+$smlhsms .

d. Select Constraint and keep the default selection of Max value.

e. Enter 0.326 in the text entry field and click Accept to save the changes and close the panel.

4. Define an objective function.

a. In the Parameters and optimization panel, select bighsrth from the Objective function drop-

down list.

b. Keep the default selection of Minimize value.



Step 7: Define Primary, Compound, and Objective Functions


1. Open the Parameters and optimization panel, if it is not already opened.


Note

Alternatively, you can click the button in the Model and solve toolbar.

2. Set up the optimization process.

a. In the Parameters and optimization panel, click the Setup tab.

b. Verify that the Optimization option is turned on, and keep all the defaults for this option.

c. Deselect Allow fast trials (single .cas file).

Note

Due to the geometry change based on the fin thickness and fin count, the fast

trials option is not possible in this problem.



d. Select Sequential solution of flow and energy equations.

3. Click Run in the Parameters and optimization panel to start the calculations.


As ANSYS Icepak starts calculating solutions for the model, the Optimization run window opens and

ANSYS Icepak displays the function values, design variables, and the running times for each optimization

iteration. In addition, the function values and design variables are plotted versus iteration number, as

shown in Figure 11.2 (p. 182).




Figure 11.2 The Optimization run Panel

Note

Each iteration takes three trials.


In this tutorial, you used the optimization tool to minimize the thermal resistance for the big heat sink.

The results show that ANSYS Icepak predicts the best (optimized) case has a fin count of 18 and a fin

thickness of 0.56 mm. In this case, the maximum temperature for the entire system is determined to

be 69.21°C (with the constraint of 70°C) while the total mass is 0.3245 kg (with the constraint of 0.326

kg). The objective function (thermal resistance) is predicted as 0.2421°C/W.


You can also try to optimize the fin count and the fin thickness of both heat sinks and the free flow

area ratios of the inlet and exit grilles. A sample case may be as follows:

• Design variables

– Fin count for the large heat sink: 2-20

– Fin thickness for the large heat sink: 0.254-2.032mm

– Fin count for the small heat sink: 2-12

– Fin thickness for the small heat sink: 0.254-2.032 mm

– Free flow area ratio of the inlet grille: 30-80%

– Free flow area ratio of the exit grille: 30-80%

• Primary functions



– Thermal resistance for the large heat sink (bighsrth)

– Mass of the large heat sink (bighsms)

– Mass of the small heat sink (smlhsms)

– Maximum temperature for the entire system: 70°C (mxtmp)

• Compound function

– Total mass of the heat sinks: 0.45 kg (totalmass)

• Objective function

– Minimize the large heat sink thermal resistance (bighsrth)



Step 11: Additional Exercise

Chapter 12: Radiation Modeling

12.1. Introduction

This tutorial demonstrates how to model radiation in ANSYS Icepak.

In this tutorial, you will learn how to include the effects of radiation in a free convection environment

with surface-to-surface (S2S), discrete ordinates (DO) and ray tracing radiation models.

12.2. Prerequisites

This tutorial assumes that you have worked on Sample Session in the Icepak User's Guide and the tutorials

"Finned Heat Sink" and "RF Amplifier" in this guide.


Radiation heat transfer becomes significant at high temperatures and is typically more important for

natural convection problems as compared to forced convection problems in electronics cooling applic-

ations. ANSYS Icepak provides three different models to solve for radiation effects: surface to surface

(S2S) model, discrete ordinates (DO) model and ray tracing model. This tutorial involves a source with

a heat sink placed on a printed circuit board (PCB) and is being cooled with natural convection. We will

first solve the model without radiation, then use the surface to surface model followed by the discrete

ordinates and the ray tracing models and lastly compare the results of all these four cases.


Open a new project and name it hsink-rad.


1. Open the Cabinet panel by double clicking the Cabinet object in the Model manager window. In

the Geometry tab, enable the Fix values option to make sure the values stay the same as we use

different units. Change all the units from m to mm. Then, input the following dimensions in the Geo-

metry tab of the Cabinet panel (Figure 12.1 (p. 186)).



Figure 12.1 Dimensions of the Cabinet and the Boundary Condition Specifications

2. In the Properties tab of the Cabinet panel, define all the sides of the cabinet as shown above. The

min y and max y sides are defined as openings while all the remaining sides are stationary walls.

3. Click Done to close the Cabinet panel.

4. The printed circuit board (PCB), heat sink base and the fins of the heat sink will be constructed using

the block object in ANSYS Icepak.

5. Create the PCB.

a. First, create a block and rename it as PCB in the Info tab of the Blocks panel.

b. Specify the dimensions of the block in the Geometry tab as shown below in Figure 12.2 (p. 187).



Figure 12.2 Dimensions of the PCB

c. Click Done to close the Blocks panel.

6. Create a new material and assign it to the PCB.

a. Right-click the Model node and select Create object and then Material. A new node called Ma-

terials will open.

b. Expand the Materials node until you reach material.1. Double click material.1 to open the Ma-

terials panel.

c. In the Properties tab of the Materials panel, choose Orthotropic from the Conductivity type

drop-down list.

i. Enter 40, 40, and 0.4 W/m-K for the X, Y, and Z directions, respectively.

d. Click Done to close the Materials panel.

e. In the Model manager window, double click the PCB object we created to open the Blocks

panel again.

f. In the Properties tab of the Blocks panel, pick material.1 from the Solid material drop-down

list.

g. Click Done to close the Blocks panel.

7. Create the heat sink base.

a. Create a new block and rename it as hs-base in the Info tab of the Blocks panel.





Figure 12.3 Dimensions of the hs-base

c. Click Done to close the Blocks panel.

8. Create the fins.

a. Create a new block and rename it as hs-fin.1.1 in the Info tab of the Blocks panel.


Note

The units depicted in Figure 12.7 (p. 192) are in mm and m.



Figure 12.4 Heat Sink Fin Dimensions

c. Leave all the other properties as their default values. Click Done to close the Blocks panel.

d. To complete the creation of the remaining fins we will use a copy procedure.

i. Right click the hs-fin1.1 object in the Model manager window and select Copy. The Copy

block hs-fin.1.1 panel opens.

ii. Set Number of copies to 8.

iii. Check the Translate option and set the X, Y and Z offset to 15, 0, and 0 mm respectively.

iv. Click Apply to close the Copy block hs-fin.1.1 panel and create the new fins.

9. Create a 75W 2D source.

a. Create a source using the Create sources button in the model toolbar.

b. In the Sources panel, specify the geometry and properties of the source according to Figure

12.5 (p. 190).

c. Click Done to close the Sources panel and complete the creation of the model.




Figure 12.5 Source at the Bottom on the Heat Sink

Tip

Alternatively, you can use the snapping tool from the object geometry area to snap

the source dimensions to those of the min z side of the hs-base block object.

The final model should appear as shown in Figure 12.6 (p. 191).



Figure 12.6 Schematic of the Model


In order to generate a fine mesh on the heat sink and the neighboring regions while retaining a

coarser mesh in the remaining part of the model, we create a non-conformal assembly enclosing all

the objects created and specify separate meshing parameters for this assembly.

1. Choose the source (source.1), base of the heat sink (hs-base), and all the fins (hs-fin1.1.x) in the

Model tree together and right mouse click to and select Create and then Assembly.

2. Double click assembly.1 in the model tree to open the Assemblies panel.

a. In the Meshing tab, click on the Mesh separately button, and specify the slack values as well as

the max sizes in each of the coordinate directions for the assembly as depicted in Figure 12.7 (p. 192).

b. This will refine the mesh within the assembly and also prevent the increase in the overall mesh

count by confining the fine mesh to within the assembly object.




Note

The units depicted in Figure 12.7 (p. 192) are in mm and m.

Figure 12.7 Meshing Parameters for assembly.1

c. Click Done to close the Assemblies panel.

3. Once the assembly creation is complete, open the Mesh control panel by pressing the Generate mesh

button.

a. Change the Mesh units to mm.

b. Input the Max element size specifications according to Figure 12.8 (p. 193).



Figure 12.8 Global Mesh Control Parameters

c. Keep all other parameters as their default values.

d. Make sure Allow minimum gap changes is checked under the Misc tab.

e. Press Generate to create the mesh.

f. You can view the mesh using the Cut plane and Surface options available in the Display tab.

g. Once you have finished viewing the mesh, make sure you uncheck Display mesh in the Display

tab, and click Close to close the Mesh control panel.


Once the model is meshed, we will solve it for different situations, i.e. with radiation off followed by

including the effects of radiation using both the view factor method as well as the discrete ordinates

and ray tracing methods available in ANSYS Icepak 13 or later.

12.8. Step 5: Solving the Model Without Radiation

1. Go to Problem setup → Basic parameters.

a. Under the General setup tab(Figure 12.9 (p. 194))

i. Make sure that solution for both the Flow and Temperature is switched on.

ii. Because this is a natural convection problem turn on the Gravity vector option.

iii. Choose Turbulent under the Flow regime group box and use the default option of Zero

equation.



Step 5: Solving the Model Without Radiation

iv. Make sure that the Radiation option is turned Off.

Figure 12.9 Basic Parameters

b. Under the Defaults tab

i. In the Ambient conditions group box, set the Temperature and the Radiation temp to

40°C.

c. Under the Transient setup tab.

i. Enter a small velocity value for the Y velocity such as 0.01 m/s.

Note

In free convection flow problems, setting a small initial velocity opposite to

the gravity vector direction is suggested.

ii. Retain the defaults for all other settings in the Basic parameters panel.

d. Press Accept to close the Basic parameters panel.

2. Go to Solution settings → Basic settings.

a. Set the Number of iterations to 400

b. Make sure the Flow is 0.001 and the Energy is 1e-7 in the Convergence criteria group box.

c. Click Accept to close the Basic settings panel.

3. Go to Solution settings → Advanced settings.



a. In the Advanced solver setup panel specify the Under-relaxation parameters of 0.7 and 0.3 for

Pressure and Momentum, respectively.

b. Select Double from the precision drop-down list at the bottom of the panel (Figure 12.10 (p. 195)).

Figure 12.10 Solution Settings

c. Keep all other default options in the Advanced solver setup panel.

d. Press Accept to close the Advanced solver setup panel.



Step 5: Solving the Model Without Radiation





12.10. Step 7: Calculate a Solution- No Radiation

1. Go to Solve → Run solution to bring up the Solve panel.

a. Enter norad as the solution ID.

b. Click on Start solution at the bottom of the panel.

c. Once the solution residuals have converged you can post process the results using plane cuts

and object faces. Note the maximum value of temperature for comparison with successive runs

wherein radiative heat transfer will be enabled in the model.

Note

You can check the maximum temperatures of each object by going to Report →Solution overview → Create.

12.11. Step 8: Surface to Surface (S2S) Radiation Model


a. In the Basic parameters panel, select On in the Radiation group box.

b. Make sure the Surface to surface radiation model is enabled.

c. Click Accept to close the Basic parameters panel.

2. To model radiation effects go to Model → Radiation form factors or use the radiation icon ( ) to

open up the Form factors panel.

a. Under Participating objects, select all objects by clicking All and leave all other settings to their

default values.

b. Press Compute to calculate the view factors.

i. You can display the view factors calculated by clicking each participating object listed under

Display object values.

ii. After reviewing the view factors, select Don't recompute.

iii. The settings for the view factor calculations setup are shown in Figure 12.11 (p. 197).

c. Press Close to close the Form factors panel.



Figure 12.11 Enabling Radiation in ANSYS Icepak Model

3. Go to Solve → Run solution and start the solver with S2S as the solution ID.

4. Once the solution residuals have converged, make note of the maximum temperature.

12.12. Step 9: Discrete Ordinates (DO) Radiation Model

Next, we will run the discrete ordinates radiation model.


a. Enable the Discrete ordinates radiation model option in the Radiation group box.

b. Press Accept to close the Radiation panel.

2. Start the solution again with DO as the solution ID.


12.13. Step 10: Ray Tracing Radiation Model

Next, we will run the ray tracing radiation model.


a. Enable the Ray tracing radiation model option in the Radiation group box.

b. Press Accept to close the Radiation panel.

2. Start the solution again with Ray as the solution ID.



Compare the maximum temperature between the runs where radiative heat transfer was enabled versus

the runs where it was not. You can clearly see that radiation is important in this model and there is a

significant difference in the maximum temperature in the field with and without radiation. Further,




there is reasonable agreement in the plane cut post processing objects obtained using the different

radiation models. Figure 12.12 (p. 199) compares the temperature fields for all the four cases.



Figure 12.12 Plane cuts on the z = 20 mm plane for (a) Radiation disabled (b) S2S radiation

model (c) Discrete ordinates radiation model and (d) ray tracing radiation model

Table 12.1 Maximum Source Temperature for Different Models

82.59°CNo radiation

75.08°CSurface to surface




76.38°CDiscrete ordinates

75.63°CRay tracing

Note

The actual values may differ slightly on different machines, so your values may not look exactly

the same.

In most models, the use of the surface to surface (view factors) model is strongly recommended. The

discrete ordinates model should be used only for very complex geometries where there are many surfaces

and computation of the view factors can become extremely computationally expensive. This is also true

when there are CAD objects present in the ANSYS Icepak model. The ray tracing model is also for

complex geometries and for objects that have large temperature variations.


In this problem we demonstrated how to model radiation in ANSYS Icepak. We first solved the model

without radiation and then used the surface-to-surface model followed by the discrete ordinates and

ray tracing methods and lastly compared the results of all four cases.



Chapter 13: Transient Simulation

13.1. Introduction

The purpose of this exercise is to demonstrate how to model and post-process transient problems.


• Define a transient problem

• Specify time-dependent parameters for objects

• Group and copy modeling objects

• Examine the results of a transient simulation, including animating results over time

13.2. Prerequisites

This tutorial assumes that you have worked on Sample Session in the Icepak User's Guide and the first

two ANSYS Icepak tutorials of this guide.


The model involves a natural convection cooled heat sink and four heat sources attached to the bottom

of the heat sink. The power dissipated by each of the four sources varies with time and peaks at 100

W.


1. Create a new project called transient.

2. From Problem setup → Basic parameters, go to the Transient setup tab, select Transient

under the Time variation group box. Then enter the Start and End times as 0 and 20 seconds, re-

spectively.

3. Click on Edit parameters and set the Time step increment to 1 s and the Solution save interval to

1. Click Accept in the Transient parameters panel and then the Basic parameters panel to save the

new time parameters.



Figure 13.1 Setting up the Model as Transient


Construct the model according to the following specifications. The final model is shown in Figure

13.4 (p. 206).

• Cabinet

0.35 mxE0.05 mxS

0.55 myE0.1 myS

0.25 mzE0.05 mzS

Open the Cabinet object panel, go to the Properties tab, under Wall type, change Min y and

Max y to Opening. Press Done and then Shift+I for an isometric view.

• Plate

SpecificationObject

Solid material:xE = 0.3 mxS = 0.1 mplate.1

defaultyE = 0.4 myS = 0.2 mGeometry:

(Al-Extruded)zS = 0.12 mRectangular

Thermal model:Plane: X-Y

Conducting thick: 10 mm


Chapter 13:Transient Simulation

• Blocks

SpecificationIRadiusRadiusHeightzCyCxCObject

Block type:0.00.02m0.06 m0.13 m0.25 m0.15 mblock.1

SolidGeometry:

Solid material:IRadius2Radius2Cylinder

default0.00.012mPlane: X-Y

(Al-Extruded)Nonuniform radi-

us

Make two copies of the tapered fin (block.1), offset by 0.05 m in the X direction (i.e., Number of

copies = 2, and Translate with X offset = 0.05 m). Select all three tapered fins, and make two

copies of this group with an offset of 0.05 m in the Y direction (i.e., Number of copies = 2, and

Translate with Y offset = 0.05 m). Remember to right mouse click on the icon in the Model tree

to copy objects. These tapered cones model a heat sink with tapered cone fins.

• Sources

The four sources have a peak power of 100 Watts each with a cycle time of 20 seconds. The variation

of power is according to the following exponential curve, = ×� � ��

, where � and � are constant,

and � is the time.

SpecificationObject

Total power = 100 WxE = 0.18 mxS = 0.12 msource.1

yE = 0.28 myS = 0.22 mGeometry: Rectangular

zS = 0.12 mPlane: X-Y

Create a source (source.1) per the specification in the table above. In the Properties tab of the

Sources panel, toggle on Transient, click Edit, and enter 0 for Start time and 20 for End time. To

specify the variation curve, click on Exponential and set a = 0.025 and b = 100. Click Update and

Done, in the Transient power panel, and then the Sources panel.




Figure 13.2 Defining Transient Power for the Sources

Now make one copy of source.1 with an offset of 0.1 m in the X-direction. Select source.1 and

source.1.1, then make one copy of these two sources with an offset of 0.1 m in the Y-direction to

complete the construction of the sources.

To view the time-dependent power specified for the sources, go to Problem setup → Basic

parameters. Select the Transient setup tab and click on View (next to Edit parameters) near the

top of this panel. This displays the time variation of the power specified using sources.



Figure 13.3 Viewing the Variation of Power on the Sources with Time

A time dependent power profile such as a piecewise linear curve can also be imported/exported

by clicking Load All/Save All in the Transient panel. Clicking Load All will open the Load all

curves file selection dialog box and override any existing data. Select the CSV file containing the

curve data and click Open.

The final model should appear as that shown in Figure 13.4 (p. 206).




Figure 13.4 Schematic of the Model


To generate a mesh for this model, go to Model → Generate mesh and specify a global maximum

element size of 0.02 m in the x, y and z directions in the Max element size group box. Across from

Mesh parameters, select Normal and keep the default global mesh settings parameters. Then go to

the Options tab and select Init element height and enter 0.005. Then click Generate to create the

mesh. Once the mesh is generated, display and examine the mesh from the Display tab. Remember to

uncheck the Display mesh option when you are done examining the mesh.

Note

The Init element height feature can be used in a relatively simple model as this one.

It is not recommended to be used for complex models as this can create very large

mesh count.


The transient settings for this model were defined at the initial stages of model building. This is required

as assigning transient power to the sources require the problem as transient a priori.

Go to Problem setup → Basic parameters. In the General setup tab, ensure Laminar is set for

Flow regime, and toggle on the default Gravity vector (i.e., X = 0, Y = -9.80665 m/s2, Z = 0). In the

Transient setup tab, give a small initial (global) velocity of 0.001 m/s in the Y direction. Accept the

changes made and exit this window.



Go to Solution settings → Basic settings and click on Reset to examine the estimated Rayleigh

number. Then go to Solution settings → Advanced settings and set the Under-relaxation

factors to 0.7 for Pressure and 0.3 for Momentum. Press Accept to close the panel.

In the Basic settings panel, set Iterations/ timestep to 100. The number of iterations per time-step

should be sufficient for the solution to converge at each time-step. Press Accept to close the panel.


Create a point monitor to monitor the temperature change with time by dragging and dropping source.1

into the Points folder in the Model tree.






Go to Solve → Run solution. In the Results tab, click Write overview of results when finished and

click Start solution.

13.10. Step 8: Generate a Summary Report

Go to Solve menu and select Define report. In the Define summary report panel, enable Specified.

Select All times in the Report time group box. Select New, hold down the Shift key and select all

blocks in the Objects drop down list. Click Accept. Click Write to display the Report summary data

panel shown in Figure 13.6 (p. 208)



Step 8: Generate a Summary Report

Figure 13.6 Define summary report Panel


Results of transient runs can be displayed in still images or animations.

To display still images, you can choose to display at a given time or a given time-step. To do so, after

creating post objects in the same manner as in a steady state run, you can go to Post → Transient

settings or click the transient settings icon ( ) to open the Post-processing time panel. To display

at a given time-step, you can toggle on Time step, and click Forward or Backward to step through

the time steps. To display at a given time, you can toggle on Time value, fill in the time to begin the

display and the time Increment, and select Forward or Backward.

To view these images in this model, create the following post-processing objects:


DescriptionSpecificationsObject

Observations: The view shows the temperature distribution on

the faces of all the blocks and the base plate. The transport of

Object: all blocks and

plate.1

face.1

thermal energy from the sources to the fins of the heatsink can

be clearly observed.Show contours/Paramet-

ers





Contours options: Solid

fill

Shading options: Smooth

Color levels: Calcu-

lated/Global limits

Post → Transient set-

tings:

Time step: 1 or Time

value: 0

Forward or Backward

Observation: The view shows air flowing from one opening to

the other. Also notice that the velocity distribution changes with

time.

Set position: Z plane

through

cut.1

center

Show vectors/Parameters

Color by: Velocity mag-

nitude

Transient: Same as the

above

To animate the above post objects, go to Post → Transient settings to open the Post-processing

time panel. Click on Animate to open the Transient animation window. To animate the current display

on screen, click on Animate in the Transient animation panel. The animation can be played once,

from the start time to end-time, or in the Loop mode.

In addition to animating the display in screen, you can also write the animation to a file in MPEG, GIF,

and some other neutral formats to be saved and played back later using a third party software. To do

that, go to Post → Transient settings, then click Animate to open the Transient animation panel.

Toggle on Write to file, then click Write to open the Save animation panel. Pick a file format, give it

a file name, and then Save. This sequence saves the entire display area with no scaling.

Alternatively, you can click on the Options tab in the Save animation panel and modify the Scale

factor in the Save animation options panel. Also available in Save animation options panel is Print

region. Choose the default Full screen or Mouse selection. Choosing Mouse selection allows one to

draw a rubber band and select only a part of the screen. To do so, choose Mouse selection, specify

the file type and file name, then click on Save in the Save animation panel. With the cursor showing

a square and the red prompt at the bottom of the screen, draw a rectangular region with the left mouse

to save it to the animation file.

You can examine how a variable changes over time at selected points using the History plot panel. To

open this panel, select History plot in the Post menu or click ( ) in the Postprocessing toolbar.

In the History plot panel, enter 20 seconds for End time, click the Add point button and select

source.1 for the point. Click the Create button to display the plot shown in Figure 13.7 (p. 210).




Figure 13.7 History plot

13.12. Step 10: Examine Transient Results in CFD Post

You can also postprocess results using tools in ANSYS CFD-Post. Go to the Post menu in Icepak and

select Write CFD Post File. Enabling this option writes out a data file (filename.cfd.dat) that can be

loaded into CFD-Post.

To launch CFD Post for a Windows system, click Start>All Programs>ANSYS 14.0>Fluid Dynamics>CFD

Post 14.0 or for a Linux system you can access CFD Post using ~ansys_inc/v140/CFD-Post/bin/cfdpost.

In CFD Post, select Load Results... in the File menu to display the Load Results File dialog box. Select

the filename.cfd.dat file that corresponds to the transient solution.



Figure 13.8 Results in CFD Post

Once the results have been loaded into CFD-Post, there are several options to view and analyze a

transient solution.

1. Display time history similar to what is displayed in Icepak.

a. Go to Insert → Text

b. Enter the text, “Auto Annotation”.

c. In the Definition tab of the Details view, enter “Time”.

d. Enable the Embed Auto Annotation option.

e. In the Type drop-down list, select Timestep.

f. Click Apply.



Step 10: Examine Transient Results in CFD Post

Figure 13.9 Details of Auto Annotation

2. Create a contour.

a. Go to Insert → Contour and create a new contour named TemperatureContours .

b. Update the settings for the Geometry tab of the Details view for TemperatureContours as

shown in Figure 13.10 (p. 213) and click Apply to create the contour (Figure 13.11 (p. 214).



Figure 13.10 Details of TemperatureContours



Step 10: Examine Transient Results in CFD Post

Figure 13.11 TemperatureContours Display

3. Display temperature at different time steps.

a. Click the timestep selector icon ( ) to display the Timestep Selector panel. Double click a

timestep to view the corresponding temperatures. See Figure 13.12 (p. 215) for details.



Figure 13.12 Timestep Selector Panel

Additional options that are available in CFD-Post can be found in "Postprocessing Using ANSYS CFD-

Post".


In this tutorial, you set up and solved a transient model and used the animation technique to examine

the results over time. Results were also examined in CFD-Post.



Step 10: Summary

Chapter 14: Zoom-In Modeling in ANSYS Workbench

14.1. Introduction

This tutorial demonstrates how to create and modify a zoom-in model (system sub-model) in ANSYS

Icepak. You will begin in ANSYS Workbench and drag an Icepak template into the Project Schematic.

An Icepak .tzr file is imported, the model is modified and solved according to the instructions in the

tutorial. The project will also include postprocessing results in CFD-Post.


• Create an ANSYS Icepak analysis in ANSYS Workbench

• Create a zoom-in model from a solved system level model

• Run that model with more detail added

• Merge the detailed system level model back into the system level model

• Postprocess results in CFD-Post

14.2. Prerequisites

This tutorial assumes that you have little experience with ANSYS Icepak and ANSYS Workbench, but

that you are generally familiar with the interface. If you are not, please review Sample Session in the

Icepak User's Guide and the tutorial "ANSYS Icepak - ANSYS Workbench IntegrationTutorial" of this guide.


The objective of this exercise is to become familiar with ANSYS Icepak's zoom-in-model capabilities.

Detailed systems can sometimes be solved first with reasonable simplifications, and then have more

detailed sub-models run from boundary conditions created from the region in question. For example,

multiple packages can be simplified as one plate with the total power of all packages. A system level

model can be solved, and a sub-region can be created with the velocities and temperatures from the

system level model and have more detail on the board in question.

In this tutorial, you will run a simplified system level model of a slotted chassis, learn how to create an

ANSYS Icepak zoom-in model, run that model and then merge the detailed section back into the original

system.





1. Start ANSYS Workbench.



Figure 14.2 ANSYS Workbench

2. Copy ICEPAK_ROOT/tutorials/rack/rack.tzr to your working directory. You must replace

ICEPAK_ROOT by the full path name of the directory where ANSYS Icepak is installed on your computer

system.

3. Drag an Icepak template from the Toolbox into the Project Schematic.

4. Right mouse click the Icepak Setup cell and select Import Icepak Project From .tzr.

5. Select Browse... and the File selection panel appears. Select the packed project file rack.tzr and

click Open.

6. The CAD model appears in the graphics display window. Click the isometric toolbar icon ( ) to display

the isometric view of the model.


Note

Look at the specifications of the different components. The model has 10 pairs of plates

(Figure 14.1 (p. 218)). If you examine any pair of plates, plate.1.x represents the PCB and

plate.2.x represents the components on that PCB. In real life each PCB would have many

components mounted on it. We are simplifying the model by representing the components

with a single plate. The thickness of these plates equals the average height of the components.

All the PCBs have the same configuration and the same components. The total power of the

components in each PCB is 30 W, so each of the plates (plate.2.x) are 30 W.

Save the problem to a new project file. This will allow you to expand on the problem without affecting

the original file.





1. In the Project text box, enter the name rack-new .

2. Click Save.

Note

ANSYS Workbench will close Icepak to save the model, you will need to launch Icepak again

to continue.


For this model, you will generate the mesh in just one step. You will specify object-specific meshing

parameters to ensure that the resulting mesh is sufficiently fine near object faces to resolve the flow

physics properly.

1. Go to Model → Generate Mesh or use the toolbar shortcut ( ) to open the Mesh control panel.

2. In the Mesh control panel, make sure Hexa unstructured is selected as the Mesh type.

3. Set the Max element size for X, Y, and Z to 0.03 m if not already set.

4. Select the Normal option next to Mesh parameters.

5. In the Local tab, select Edit next to Object params (Figure 14.3 (p. 221)). Verify that the individual

localized mesh settings for the following objects are:

Requested ValueParameterObject nameObject type

10Y countAll openingsOpenings

0.003Low end heightAll platesPlates

0.003High end height

4Y countblock.3Block

Note

You can also set mesh parameters by right clicking object in the Model tree and select-

ing Edit mesh parameters.



Figure 14.3 Object Parameters in the Mesh control Panel

6. Press Done to close the Per-object meshing parameters panel.

7. In the Settings tab of the Mesh control panel, Generate the mesh and then display and check the

mesh quality from the Display tab. Uncheck the Display mesh option when you are done.


1. Go to Solution settings → Basic settings and Solution settings → Advanced settings

, and verify that the following values are set for each variable:




2. Go to Problem setup → Basic parameters and make sure the Flow regime is Turbulent and

the turbulence model is Zero equation under the General setup tab. Press Accept to close the panel.

3. Now add two temperature point monitors for plate2.1 and plate2.2 into the Points folder to observe

the progress of the solution at the center of the objects. To do this, highlight both objects in the

Model tree using the Ctrl key and the left mouse button, and then drag objects into the Points folder.

The default setting for a monitor point is temperature so nothing else has to be done.









1. Go to Solve → Run solution menu and turn on Sequential solution of flow and energy equations

in the General setup tab.

Note

When gravity is not turned on in the solution, you have the opportunity to reduce

solve time if desired by selecting this option. Since there are no buoyancy effects, there

is no longer a coupling of the Navier-Stokes and energy equations. Thus, you can

completely converge the flow equations and then use that value in the energy equation

instead of solving both on every iteration.

2. Click Start solution to run the solver.


1. After the solution has converged, create the following post processing objects:


Object-face view of temperature on plate2.2Object: plate2.2face.1

Observation(s): Note the min & max temperatures and the

temperature distribution.

Show contours/Paramet-

ers


Contours options: Solid fill

Shading options: Banded

Contour levels:

Level spacing: Fixed/

Number = 20

Calculated: This object

Objects-face showing the flow pattern.Object: all fansface.2




Observation(s): Animate the particle traces. If you want to see

motion from start to end, turn off particles and animate the

traces.

Show particle

traces/Parameters

Variable: Speed

Display options: Uniform

= 50

Style: Dye trace and

Particles

Plane cut (x-y) view of the velocity vectors in the z plane.Plane location:cut.1

Observation(s): Flow patterns (especially around the plates)Set position: Z plane

through center

Show vectors

Plane cut (y-z) view of the velocity vectors in the x plane.Plane location:cut.2

Observation(s): Flow patterns (especially around the plates)Set position: X plane

through center

Show vectors

face.1 and cut.1 should look similar to Figure 14.4 (p. 223) and Figure 14.5 (p. 224).

Figure 14.4 face.1 (Plate2.2 Temperature)




Figure 14.5 cut.1 (Z-Plane Through Center Velocity)

2. Finally, save all the postprocessing objects created. Go to Post → Save post objects to file. Save it

with default file name post_objects to be used in future.

14.11. Step 8: Create a Zoom-In Model

With a solution obtained for the main model, we can now zoom-in around one pair of PCB-components

plates, namely plate.1.2 and plate.2.2.

1. Go to Post → Create zoom-in model. The Zoom-in modeling panel appears. The boundaries for

the zoom-in also appear in the ANSYS Icepak main window as a bold white box. By default this zoom-

in box is coincidental with the cabinet.

2. Resize this box by entering the values shown in Figure 14.6 (p. 225) into the zoom-in window. Be sure

to change Max Y to an outflow and Min Z and Max Z to walls. (Please note that the zoom-in box now

surrounds plate.1.2 and plate.2.2 and includes portions of some on the remaining system level model

objects (Figure 14.7 (p. 226)).) There needs to be one outflow to compensate for slight differences in

flow with a pressure differential. The wall objects are created since the entire face on that side is created

in a solid or on a solid surface.



Note

The coordinates for each of the zoom-in boundaries can also be specified by clicking

the Select button to the right of the appropriate text entry box and clicking the left

mouse button on the desired point in the graphics display window. You may want to

orient your view depending upon the coordinate being selected to ensure a more ac-

curate selection. The boundaries of the zoom-in model will be displayed in the graphics

window as you update them.

Figure 14.6 The Zoom-in modeling setup Panel

3. Click on Accept to create the zoom-in model. Since many of the parts in the zoom-in model extend

out of the zoom-in box, a warning message window should appear listing a set of objects that lie

outside.

4. In the Objects overlapping dialog box, click the Resize button to resize these parts to fit into the

zoom-in model. ANSYS Icepak writes out a zoom-in model called rack-new.zoom_in. ANSYS Icepak re-

ports on the operations to construct the model and creates the profiles in the ANSYS Icepak messages

window.



Step 8: Create a Zoom-In Model

Figure 14.7 Zoom in Box

14.12. Step 9: Edit the Zoom-in Model

1. Set up a new Icepak template in same ANSYS Workbench project. Then link a Results cell to this Icepak

component. The Results cell should link to the Icepak Solution cell.

2. Right mouse click the Icepak Setup cell and select Import Icepak Project

3. In the file selection dialog, select the zoom-in model called rack-new.zoom_in. (It will be in the same

location as the folder for the system level model.) In the system level model we used a single conducting



thick plate to represent the components. We can now replace the plate.2.2 by the individual compon-

ents.

4. Double click plate.2.2 to open the Plates panel and make the following changes:

ValueField

Info

ChipName

Geometry

Start / lengthSpecify by

0.05 mYL

-0.05 mZL

Properties

3.0 WPower

5. Create nine additional components in an array.

a. Right mouse click Chip and select Copy.

b. Create two copies of Chip with an Z-offset of -0.065 m.

c. Select and highlight all three Chip plates in the Model tree.

d. Make three copies of the three plates with an Y-offset set to 0.07 m in the same way you copied

the singe chip.

e. View the geometry in isometric view (Shift+I).

f. Delete two of the components to form the pattern shown in Figure 14.8 (p. 228).



Step 9: Edit the Zoom-in Model

Figure 14.8 Schematic of the Completed Zoom-in Model

14.13. Step 10: Mesh the Zoom-In Model

1. Go to Model → Generate mesh, and set the Mesh type to Hexa unstructured and the Mesh

parameters to Coarse.

2. In the Local tab, turn off the Object params.

3. In the Global tab, enter the following global mesh settings:

Table 14.1 Global Settings for Zoom-in Model

0.003 mMax element size for X:

0.02 mMax element size for Y:

0.02 mMax element size for Z:

2Min elements in gap

1Min elements on edge

3Max size ratio

The meshing panel should now look like Figure 14.9 (p. 229).



Figure 14.9 Zoom-in Mesh control Panel

4. Generate the mesh and then display and check the mesh quality from the Display tab. Make sure to

uncheck the Display mesh option when you are done.

14.14. Step 11: Zoom-In Physical and Numerical Settings

1. Drag and drop the two chips in the corners of the top row (chip.5 and chip2.3) into the Points folder

in the Model tree to monitor the temperature at the centers of these two chips.

2. Delete the monitor point plate.2.2 brought in from the system level model (it no longer exists as an

object).

3. Go to Solution settings → Basic settings to change the maximum number of iterations to 300.

4. Solve the model by selecting Solve → Run solution and by clicking on Start solution under the

General setup tab.

14.15. Step 12: Examine the Zoom-in Results

After the solution has converged, create the following postprocessing objects and compare the results

with the system level models.


ject

Object-face view of temperature on all chipsObject: all chipsface.1

Observation(s): Note the min & max temperatures and the

temperature distribution.

Show contours/ Para-

meters



Step 12: Examine the Zoom-in Results


ject

Contours of: Temperat-

ure

Contours options: Solid

fill

Shading options:

Smooth


Object-face showing the flow patternObject: side_open-

ing.miny

face.2

Observation(s): Note the flow pattern on both sides of

plate1.2 and over the components. Animate the particle

traces.

Show particle traces/

Parameters

Variable: Speed

Particle options

Start time: 0; End time:

1

Display options: Uni-

form = 100

Style: Dye trace and

Particles

Figure 14.10 (p. 231) shows the two object faces at the same time.



Figure 14.10 face.1 and face.2


If we were to model all the components in the system level model, we could have ended up with a cell

count of about 10 times the size of the zoom-in model. The simplifications at the system-level enabled

us to quickly solve the system level model. The zoom-in model showed us the temperature variation

at the card level, which was essential to identify the correct locations of the hot spots.

14.17. Step 14: Additional Exercise 1

Set up this problem in a Workbench based Icepak project. Then set up another Icepak component in

the same Workbench project schematic and replace the PCB plate with a detailed PCB object and

postprocess the results in CFD Post.



Step 14: Additional Exercise 1

You can then perform a comparison study in CFD Post by setting up a third Icepak component. This

time duplicate the first Icepak component and link this component to the available Results component.

Post process the results in CFD Post and compare them to the results containing the PCB plate object.

14.18. Step 15: Additional Exercise 2

Additional exercise may be performed to create a non-conformal mesh assembly surrounding the details

of the third PCB in the main model. Then, the results obtained using non-conformal meshed assembly

may be compared to the results obtained using the main model with the conformal mesh and to the

ones from the zoom_in approach with conformal mesh.

1. Save the rack-new.zoom_in model with a new model name such as rack.zoom_in_merge.

2. Delete all the components within the model except all the plates which represents the PCB and the

chips and re-save the model. (This version has all the unnecessary components for the system merge

removed.)

3. Open the main model rack.

4. Save it as rack-merge-NC.

5. Use File → Merge Project to import rack.zoom_in_merge into this model with all the details of

chips.

6. Deactivate the old components residing where the merged components are ( plate.1.2 and plate.2.2).

7. Create a non-conformal assembly containing all the chips and the board. It is suggested a slack value

of 3-5 mm in all directions for the assembly is a good value to start without violating any of the rules.

8. Finally, mesh and run the model with a different solution ID and compare the results to the previously

obtained ones. Verify that the results are very comparable.

Figure 14.11 (p. 233) shows a temperature comparison between the zoom-in model and the system

level model with a non-conformal assembly. While the temperatures are slightly different, the

overall distribution (hot spots) stay the same.



Figure 14.11 Temperature Comparison: Zoom-in vs. System with Non-conformal

assembly



Step 15: Additional Exercise 2

Chapter 15: IDF Import

15.1. Introduction

This tutorial demonstrates the “IDF" import capability of ANSYS Icepak.


• Import IDF files.

• Apply the various options offered in ANSYS Icepak's IDF import capability.

15.2. Prerequisites


solved or read the tutorial "Finned Heat Sink". If you have not, please review Sample Session in the

Icepak User's Guide.


Intermediate Data Format (IDF) is a data exchange specification between ECAD and MCAD for the design

and analysis of printed circuit boards. An IDF CAD model is generated by software such as Mentor

Graphics. Typical IDF models include a board file and a library file. The board file includes board layout

(board dimension and shape, location of the components), and the library file includes component in-

formation (size, power dissipation, junction to case and junction to board thermal resistance, etc.). ANSYS

Icepak's IDF import utility is designed to convert the IDF CAD data into an ANSYS Icepak model auto-

matically. ANSYS Icepak imports the geometry as well as parameters such as power and material property

based on the availability of such information.

This tutorial does not involve generating a mesh, calculating a solution or examining results. These

steps will not be shown in this tutorial.


1. Start ANSYS Icepak, as described in Starting ANSYS Icepak on a Linux System and Starting ANSYS Ice-

pak on a Windows System of the User's Guide.






3. Specify a name for your project.

a. In the Project name text box, enter the name idf-demo .

b. Click Create.


To build the model, you will first import the board layout. The board and the associated library files

have to be chosen at this step.

File → Import → IDF file

Figure 15.1 IDF Import Menu

1. In the IDF import panel, click the Browse button next to the Board file (ascii) field and select the

file (brd_board.emn ). Board files have the extension “*.emn" or “*.brd". Note that the library file

(brd_board.emp ) gets loaded automatically. Specify Project Name as tutorials/idf_import(Figure 15.2 (p. 236)).

Figure 15.2 IDF import Panel - Load files

2. Click Next and go on to the Layout options section (Figure 15.3 (p. 237)). Retain all default settings:



• Import type as Detail

• Board plane as XY - this is always detected automatically

• Board shape as Rectangular

• Board properties - Click Edit button to access the Board properties where you can enter details

such as number of trace layers, coverage and layer thickness etc. Layer properties refer to the av-

erage properties of all internal layers. In this example, examine the defaults, and click Cancel to

close the Board properties panel.

Note

More advanced PCB models are covered in the introductory tutorial, "RF Amplifier",

and application tutorial, Trace Layer Import for Printed Circuit Boards (p. 267) located

in this guide.

• Drilled holes are for positioning purposes and usually are not thermally important. During the import,

they can be ignored. By default, ANSYS Icepak leaves import drilled holes unchecked under Detailed

options.

• Enable Make all components rectangular under Detailed options to convert all polygonal com-

ponents to prisms.

Figure 15.3 IDF import Panel - Layout options

3. Click Next to go to the Component filters section (Figure 15.4 (p. 238)). Components can be filtered

either by size and power or by component type. For now, select Filter by component type and Import

all components. The other options will be explained in more detail at the end of the tutorial.




Figure 15.4 IDF import Panel - Component figures

4. Click Next to go to the Component models section (Figure 15.5 (p. 238)).

5. Select Model all components as and keep the default settings. The option Choose specific component

model will be discussed later in the tutorial.

Figure 15.5 IDF import Panel - Component models

6. Click on Next to go to the Miscellaneous options section (Figure 15.6 (p. 239)). Select Append Part

Name to Reference Designator under the Naming conventions group box.



Figure 15.6 IDF import Panel - Miscellaneous options

7. Click Finish to complete the import.

8. Examine the imported model (Figure 15.7 (p. 240)).

Observe:

• the different types of blocks

• the material properties of the PCB block, which is called BOARD_OUTLINE.1

• the power and resistance values of the network blocks, if any.

Note that:

• The components form into groups according to types automatically

• You can use the edit function under groups to change properties for all the components in the

same group at one time

• You should check message windows for missing properties.

Figure 15.7 (p. 240) shows ANSYS Icepak model with components modeled as 3D objects (solid

blocks or two-resistor network blocks). Appropriate boundary conditions need to be applied before

starting thermal analysis. In addition, you can review power values by selecting the Power and

temperature limit option in the Model menu.




Figure 15.7 IDF Imported Model with All Components

15.6. Step 3: Component Filtration Alternatives

1. If Filter by size/power is chosen (Figure 15.8 (p. 240)), the size filter and/or power filter may be specified.

Only those components that are either larger than the specified size filter, or dissipate more than the

specified power filter, are imported. If these fields are ignored, all components are imported.

Figure 15.8 IDF Import Panel - Components filters: Filter by size/power

2. If Filter by component type is chosen (Figure 15.9 (p. 241)), the required components can be selected

through the Component selection panel (Figure 15.10 (p. 241)); otherwise all the components are in-

cluded. The Component selection panel contains reference designators for all components.



Figure 15.9 IDF Import Panel - Component filters: Filter by component type

After clicking Choose, you can choose individual components from the panel in the figure below:

Figure 15.10 Component selection Panel

15.7. Step 4: Component Models Alternatives

1. The Model all components as option is available through both filtration mechanisms.

2. The Choose specific component model option is available when filtering by component type. ANSYS

Icepak allows the component property to be added if no thermal information is available from the IDF

file (IDF 2.0), or modify properties if it is available (IDF 3.0).

3. Under Choose specific component model, properties of required components can be loaded from

an existing file using the Load data from file option. The format for the file is:

Rjb (C/W)Rjc (C/W)Power (W)Reference designator

Figure 15.11 (p. 242) shows a sample file. Objects not present in the file are imported with data

already present in the IDF file, or as solid blocks with no power specification.



Step 4: Component Models Alternatives

Figure 15.11 Set Component Property Using File

4. Component properties may also be edited manually by selecting the Specify values for individual

component types option. The components to be imported are listed under Selected components.

The component name is composed of the type and name and the number of copies, followed by a

more descriptive part name (Figure 15.12 (p. 242)). To manually set the component property, you can

select the component in the Selected components list. Multiple selections can be made with Ctrl +

left mouse or Shift + left mouse. Then, you can choose the model type: Two-resistor (Rjc-Rjb), 3d

blocks, or 2d sources, and specify power. For a two-resistor model, Rjc and Rjb values need to be

specified as well. After inputting your specifications, you can click Apply to complete the modification.

Figure 15.12 Manual Selection of Component Models


IDF import capability of ANSYS Icepak was used to import a board level model with all components. It

was observed that the board properties and component properties (where specified) were automatically



updated in the ANSYS Icepak model. Components filtration and modeling alternatives that are available

in the IDF import mechanism, were also discussed.



Step 5: Summary

Chapter 16: Modeling CAD Geometry

16.1. Introduction

Complex geometries are common in today's electronics cooling applications. Examples include complex

enclosure shapes, heat sink fins, louvers, etc. Proper accounting of the geometry of these objects is

important for accurate prediction of flow and heat transfer. Modeling of these complex geometries is

possible by using the direct CAD modeling feature in ANSYS Icepak. The hex-dominant mesher is used

to create an unstructured mesh for these complex shapes.

This tutorial demonstrates how to use the hex-dominant mesher to create an unstructured mesh for

complex shapes in ANSYS Icepak.


• Use a CAD object and create an unstructured mesh using the hex-dominant mesher.

• Solve for flow and heat transfer in a model.


16.2. Prerequisites


miliar with the interface. If you are not, please review Sample Session in the Icepak User's Guide.


The cabinet contains a heat sink 1 with extruded fins having aerofoil cross section, mounted on a block

with a heat source placed between them. These objects are placed in a wind tunnel setup as shown in

Figure 16.1 (p. 246).

1The heat sink used for this sample problem was obtained from the company Alpha, www.alphanovatech.com/cindexe.html#w.



Figure 16.1 Wind Tunnel Model with Heatsink Modeled as CAD Block

16.4. Step 1: Creating a New Project








a. In the Project name text box, enter the name shapes .

b. Click Create.

Note

ANSYS Icepak creates a default cabinet with the dimensions 1 m × 1 m × 1 m and

displays the cabinet in the graphics window.


To build the model, you will first create the CAD block representing the heat sink. You will need to

import the required CAD file into ANSYS Icepak. ANSYS Icepak can import CAD files in step and IGES

formats.

1. Import the IGES/Step file into ANSYS Icepak

a. Go to Model → CAD data.

b. Select Load in the CAD data panel and click on Load IGES/Step file.

c. Select w35-20.stp in the File selection panel and click Open.




d. The CAD model appears in the graphics display window.

2. In the CAD data panel, select the surfaces to be used to create the CAD block.

a. In the Creation mode section of the CAD data panel, ensure Selected is enabled.

b. Select Use CAD surfaces directly.

c. In the Create object section, select Blocks.

d. Drag a rectangular region around the displayed CAD model to select the surfaces to be used to

create the CAD block. Clicking on the middle mouse button creates the block (e.g., F_4074 or

similar name) which can be used in the ANSYS Icepak model. In the CAD data panel, under Fam-

ilies, click None to hide all CAD lines and surfaces.



e. Close the CAD data panel.

3. Resize the default cabinet in the Cabinet panel.

Model → Cabinet

a. In the Cabinet object panel, click the Geometry tab.

b. Under Location, enter the Start/end coordinates shown in Table 16.1: Coordinates for the Cabin-

et (p. 249) :

Important

Note that the dimensions are in mm.

Table 16.1 Coordinates for the Cabinet

150 mmxE-100 mmxS

20 mmyE-5 mmyS

25 mmzE-25 mmzS

c. Click Update to resize the cabinet.

d. In the Orient menu, select Isometric view to scale and orient the view of the cabinet to fit the

graphics window (Figure 16.2 (p. 250)).




Figure 16.2 Creating the Heat Sink CAD Block From a CAD File

4. Edit the cabinet properties to specify the Min x and Max x sides as openings.

a. Select Opening from the drop-down menu under Wall type for Min x and Max x.

b. Select Edit to display the Openings object panel for Min x and specify the � velocity to be 5 m/s.



c. Press Done in the Openings object panel and then the Cabinet object panel to apply the changes

and close the panels.

5. Create a block at the base of the heat sink.

a. Click the Create blocks button ( ) to create a new block.

ANSYS Icepak creates a new solid prism block in the center of the cabinet. You need to change

the size of the block.

b. Click the Edit object button ( ) to open the Blocks panel.


d. Enter the Start/end coordinates for the Prism block as shown in Table 16.2: Coordinates for the

Block (p. 252).




Important


Table 16.2 Coordinates for the Block

30 mmxE-30 mmxS

0 mmyE-5 mmyS

25 mmzE-25 mmzS

The block touches the cabinet in the Min y direction, and the heat sink in Max y. The Min z

and Max z sides of the block touch the cabinet.

e. In the Properties tab, select Solid for the Block type if not already selected. Under Thermal

specification, keep default as the Solid material. Because the default solid material is extruded

aluminum, you need not specify the material explicitly here.

f. Click Done to modify the block and close the panel.

6. Create a source between the base block and the heat sink.

a. Click the Create sources button ( ) to create a source.

b. Edit the source Geometry with the Start/end dimensions given in Table 16.3: Coordinates for the

Source (p. 252).

Important


Table 16.3 Coordinates for the Source

X-ZPlaneRectangularShape

10 mmxE-10 mmxS

—yE0yS

-10 mmzE10 mmzS

c. Edit the source Properties and specify a Total power of 50.0 Watts.



d. Click Done to modify the source property and close the panel.

Note

We will allow heat transfer from the base of the metal block by creating a wall, wall.1

on the Min y side of the block and the cabinet boundary.

7. Create a wall at the base of the metal block.

a. Edit the wall Geometry with Start/end dimensions given in Table 16.4: Coordinates for the

Wall (p. 253).

Important


Table 16.4 Coordinates for the Wall

X-ZPlaneRectangularShape

30 mmxE-30 mmxS

—yE-5 mmyS

25 mmzE-25 mmzS




b. Edit the wall Properties to specify the boundary conditions of the wall.

i. Select Heat transfer coefficient from the External conditions drop-down list.

ii. Press Edit to open the Wall thermal conditions panel.

iii. Select Heat transfer coeff in the Thermal conditions group box.

iv. Input a Heat transfer coeff of 10 W/km2 and keep the default selection of Constant in the

Heat transfer coefficient group box. The Reference temperature is ambient.

Figure 16.3 Specifying Boundary Condition for the Wall

v. Press Done in the Wall external thermal conditions panel and then the Walls object panel

to apply the changes close the panels.

The final model should correspond to the one shown in Figure 16.1 (p. 246).




1. In order to properly mesh the heat sink, a fine mesh needs to be used in that region. To reduce the

overall mesh count, the finely meshed region should be secluded using a separately meshed assembly.

a. Choose the heat sink (F_4074 or similar name) and source.1 from the Model tree and create

an assembly called assembly.1 .

b. The meshing parameters for this assembly are shown in Figure 16.4 (p. 255).

Important



Note

The slacks in the Min Z and Max Z directions are specified by snapping with the

cabinet boundary in the respective directions. Note the use of Max element size

in each direction to control the mesh refinement in the assembly.

c. Press Done to close the Assemblies panel.




2. Another separately meshed assembly, assembly.2 is created with assembly.1 to enable a smooth

transition of the fine mesh in assembly.1 to the relatively coarse mesh in the outer regions of the

model.

a. Choose assembly.1 , block.1 and wall.1 from the Model tree and create assembly.2 .

b. The meshing parameters for this assembly are shown in Figure 16.5 (p. 256).

Important



Note

There is a larger max grid size in this assembly compared to assembly.1.


3. Go to Model → Generate mesh.

a. Keep the default selection of Mesher-HD for the Mesh type and input the settings shown in

Figure 16.6 (p. 257) below.



Important


Figure 16.6 Mesh control Panel Inputs

Note

When meshing models containing CAD blocks, you could select Hexa unstructured

or Hexa cartesian for the global Mesh type, but only Mesher-HD should be used

to mesh CAD blocks. Therefore, you must create assemblies with Mesher-HD as

the Mesh type around all the CAD blocks.

b. Click Generate to create the mesh.

4. The surface mesh on the heat sink and the mesh on the center “y" plane is shown in Figure 16.7 (p. 258).

The relatively coarse mesh in the overall cabinet, the intermediate mesh in assembly. 2 and the fine

mesh in assembly.1 is clearly seen in the central “y" plane view of the mesh as shown in Figure

16.8 (p. 258).




Figure 16.7 Mesh Near Heat Sink

Figure 16.8 Y-Plane View of Mesh



a. In the General Setup tab, make sure that both the flow and the temperature fields are switched

on.

Note

This is a forced convection problem; therefore the natural convection as well as

radiation effects can be ignored.



b. Switch off the Radiation and make sure Gravity vector is unchecked.

c. Choose Turbulent and then Zero equation in the Flow regime group box.

Note

The problem being dominated by forced convection, a sequential solution of flow

and energy equation shall be used.

d. Press Accept to save the settings and close the panel.

2. Under Solution settings → Basic settings, specify the number of iterations to 300, the Flow

convergence to 0.001 and the Energy convergence to 1e-14, as shown in Figure 16.9 (p. 260), and press

Accept to save the settings and close the panel.





3. Stringent energy convergence criterion is required when the energy equation is solved separately.

Go to Solution settings → Advanced settings.

a. Make sure that the Under-relaxation parameters for Pressure and Momentum are 0.3 and 0.7

respectively.

b. Input the following for Temperature in the Linear solver group box:

i. Choose W from the Type drop-down list.

ii. Enter 1e-6 for the Termination criterion and the Residual reduction tolerance.

c. Change Precision to Double.



Figure 16.10 Advanced solver setup Panel

Note

These settings are used for separate solution of the energy equation

d. Press Accept to save the changes and close the panel.








Note

You can click the save project button ( ) in the File commands toolbar.



Step 5: Save the Model


1. Go to Solve → Run solution to display the Solve panel.

a. Enable Sequential solution of flow and energy equations.

b. Click Start solution to start the solver.

ANSYS Icepak begins to calculate a solution for the model, and a separate window opens

where the solver prints the numerical values of the residuals. ANSYS Icepak also opens the

Solution residuals graphics display and control window, where it displays the convergence

history for the calculation.

Note


plot may not look exactly the same as Figure 16.11 (p. 262).

Figure 16.11 Residuals

c. Click Done in the Solution residuals window to close the panel.




The distribution of the different quantities on the CAD heat sink can be visualized using the object face

option, as in any other ANSYS Icepak object.

1. Click the Object face button ( ) under the Postprocessing toolbar.

a. Choose the CAD block from the Object drop-down list

b. Click on Show contours and then Parameters to open the Object face contours panel.

c. Keep the default selection of Temperature in the Contours of drop-down list.

d. Keep the default selection of Solid fill in the Contours of group box.

e. Select Smooth in the Shading options group box.

f. Keep the default selection of Calculated in the Color levels group box and choose This object

from the drop-down list.

Figure 16.12 Post Object Face Settings for CAD Block

g. Press Done in the Object face contours panel and then in the Object face panel to close the

panels and view the postprocessing object.




This maps the color range to the temperature distribution on the heat sink. The temperature on

a given point can be seen using the surface probe tool.

Figure 16.13 (p. 264) shows the temperature distribution on the heat sink.

Figure 16.13 Temperature Distribution on the Heat Sink

2. Right click face.1 in the Model tree and deselect Active to deactivate the postprocessing object.

3. Click the Plane cut button ( ) under the Postprocessing toolbar.

a. Select Y plane through center from the Set position drop-down list.

b. Select Show vectors option.

c. Click Create and Done. Zoom in to display more details.

The velocity field around the heat sinks fins, visualized on the central y -plane, is shown in Figure

16.14 (p. 265).



Figure 16.14 Velocity Field Around the Heat Sinks Fins


In this tutorial, you imported a CAD object and set up a problem. You then created an unstructured

mesh using the hex-dominant mesher. This forced convection problem was solved for flow and heat

transfer and the results were examined on object faces and cut planes in the model.



Step 8: Summary

Chapter 17: Trace Layer Import for Printed Circuit Boards

17.1. Introduction

A printed circuit board (PCB) is generally a multi-layered board made of dielectric material and several

layers of copper traces. From the thermal modeling point of view, a PCB may be treated as a homogen-

eous material with bi-directional thermal conductivity, i.e. thermal conductivity value is different in the

normal-to-plane direction than that of the in-plane direction. This approach is reasonable as long as

the trace distribution is more-or-less uniform in any given layer. However, with the continuing challenges

to increase product functionality while decreasing product size, designers are compelled to place more

and more functionality on individual PCB's. As PCB's become more densely populated, their trace layers

are becoming more non-uniform and it is prudent to use locally varying thermal conductivity information

on the board.

PCBs often have large copper spread in the power and ground planes, this along with the presence of

vias (especially thermal vias) can be effectively used by the designer to spread heat from the package.

A detailed conductivity map of the pcb is required to simulate heat transfer, which is possible in Ansys

Icepak using the trace feature.

Conducting a computational heat transfer simulation for each individual layer is costly and impractical

for a system level model. In ANSYS Icepak, it is possible to import trace layout of the board and compute

locally varying orthotropic conductivity (kx, ky, and kz) on the board using a profile mesh size. The sup-

ported file formats are (1) MCM, BRD and TCB files and (created using Cadence, Synopsys, Zuken, and

Mentor), (2) ANF files and (3) ODB++ files.

Ansoftlinks installation and licensing is required to create ANF files to be read by Icepak. Icepak can

read ODB++ files, but an Ansoftlinks license is required. To import MCM/BRD files, Cadence Allegro

must be installed.

In this tutorial, we will show :

• How to import trace layout of a typical PCB in TCB format and solve two sample cases based on the

trace layout information.

• How to use Model layers separately option for better accuracy.

• How to import Gerber format layer and via files.

17.2. Prerequisites







A PCB board, library files and traces are imported to create the model. The model is first solved for

conduction only, without the components and then solved using the actual components with forced

convection.







a. In the Project name text box, enter the name trace-import .

b. Click Create.


To build the model, you will first import the board layout. The board and the associated library files

have to be chosen at this step and the trace file can be imported later.

File → Import → IDF file

1. In the IDF import panel, select the board (A1.bdf ). You can keep the default project name A1, specify

the model directory using Browse and click on Next.

The associated library files are imported automatically.

2. Select Next to see your Layout options. Keep Detail for the Import type, XY for the board plane

and Rectangular for the board shape.


Chapter 17:Trace Layer Import for Printed Circuit Boards

Note

Because we import the trace information later, we do not need to edit the board

properties at this time.

3. Select Next to see the Component filtering options. Ensure Import all components is selected.

Note

You can filter certain components at this step by their size and power information, i.e.

you can ignore the small components or the ones dissipating low power. We will import

all of the components in this tutorial.

4. Select Next to see the Component models section. Select Model all components as. Keep the default

selection of 3d blocks and the default Cutoff height for modeling components as 3d blocks.




Note

If you have thin components on your board, they can be modeled as 2D sources. In

this tutorial, we would like to model all the components as rectangular blocks.

5. Click Next to go to the Miscellaneous options section where you can specify the naming and monitor

options. Keep the default options and click Finish to start importing the files. This will take some time

depending on the speed of your machine.



You have learned how to import board and library files, and in general you can import any IDF

file by using the procedure above.

The next step in building the model is to import the trace files. A pre-built board model named

“A11" (see Figure 17.1 (p. 271)) will be used to demonstrate the trace file import. This pre-built

model was extracted from the previous board file (A11.brd), a number of small components were

removed and a non-conformal assembly was formed.

Figure 17.1 A11 Board Layout

a. Unpack A11.tzr file to your desktop and name the project “A11".




Note

As mentioned earlier, the trace file (.brd, .tcb, .mcm, .anf, or .odb++) can either be

imported during the IDF file import or the trace layout information can be assigned

to the board after importing the IDF file.

b. Right click BOARD_OUTLINE.1 in the Model manager window and click Edit to display the Blocks

object panel.

To import the trace layout, follow the procedures below.

i. In the Geometry tab, select ASCII TCB from the Import ECAD file drop down list (Figure

17.2 (p. 272)).

Figure 17.2 Blocks [BOARD_OUTLINE.1] Panel

ii. Select A1.tcb from the Trace file panel. This process may take a few minutes depending on

the speed of your computer.

iii. Once the import process is completed, you can edit the layer information in the Board layer

and via information panel (Figure 17.3 (p. 273)).

The number of layers in the board will automatically be imported to ANSYS Icepak and

you will have to enter the thickness of each layer and the material type. In this tutorial,

the metal layers are pure Cu and the dielectric layers are FR-4.



iv. Enter the layer thickness as shown in Table 17.1: Thickness Information on the Board (Layer 1:

Top, Layer 7: Bottom layers) (p. 273) and choose 100 rows and columns.

Table 17.1 Thickness Information on the Board (Layer 1: Top, Layer 7: Bottom

layers)

Thickness (mm)Layer

0.04Layer 1

0.45364Layer 2

0.062Layer 3

0.467Layer 4

0.055Layer 5

0.442Layer 6

0.045Layer 7

Figure 17.3 Importing Trace Layout and Editing Layer Information

v. By default, layers are lumped for each sub-grid, therefore, the Model layers separately option

is off. They can also be modeled separately, which will be discussed later when the Model

layers separately option is used.




vi. Via information (e.g., material, plating thickness, filled/un-filled, via diameter etc.) is imported

automatically (Figure 17.4 (p. 274)), keep the default settings.

Figure 17.4 Vias Information

vii. Click Accept to save your settings.

Note

The background mesh matrix (rows and columns) is used to compute the

orthotropic conductivity on the board. The rows represent the division of the

board in the y-direction, the columns represent the division of the board in

the x-direction and the size field determines the divisions of the board and

indicates the grid size in each direction. The values of k, kx, ky, and kz on each

cell are determined by the local trace density and the direction. ANSYS Ice-

pak does not include the trace geometry in the physical model; however, the

locally varying orthotropic conductivity is mapped from the background mesh

to the physical model mesh. Once the trace file is imported and assigned to

the board geometry, the trace layers are associated with the board and are

moved (in translation and/or rotation) with the board object.



viii. Press Done to close the Blocks object panel.

ix. Right click on the object BOARD_OUTLINE.1 and go to Traces from the menu.

Note

You can view the traces in three different ways, i.e. single color, color by

layer, or color by trace. Each of the trace layers can be viewed separately by

switching the visible option on or off in the layers part of the panel. (Figure

17.5 (p. 275)).

Figure 17.5 Displaying Traces on the Board

x. Select color by trace; the board traces are as shown in Figure 17.6 (p. 276).




Figure 17.6 Trace Layout on the PCB with the Color by trace Option

17.6. Conduction Only Model (PCB Without the Components)

Follow these steps for a conduction-only model:


You will generate a mesh for each sample problem. First we will consider a board without any compon-

ents.

1. Make all objects (including the openings) inactive except the BOARD_OUTLINE.1 object.

2. Select the cabinet and select Autoscale from the Edit window to make the size of the board and the

cabinet the same.

3. Go to the Properties tab of the Cabinet object panel, and select Wall from the Min z and Max z drop-

down lists.

4. Press Edit next to Min z to open the Walls object panel.

a. In the Properties tab, select Temperature from the External conditions drop-down list, and

keep the ambient temperature (20°C).

b. Press Done to close the panel.

5. Press Edit next to Max z to open the Walls object panel.

a. In the Properties tab, specify a Heat flux of 50000 W/m2 in the Thermal specification group

box.




Note

The rest of the sides are insulated. The board will be simulated using a conduction-

only model.

6. Press Done to close the Cabinet panel.

7. Go to Model → Generate mesh to open the Mesh control panel.

a. Make sure the Mesh type is Mesher-HD.

b. Specify a Max element size for X, Y, and Z as 5, 3, and 0.05 mm respectively, and a Minimum

gap of 1 mm in all three directions.

c. Keep all other defaults and click Generate.

8. Once the mesh has been created, Close the Mesh control panel.

17.8. Step 2: Set Physical and Numerical Values


a. Since this is a conduction only model, toggle off the Flow option in the General setup tab.

b. Make sure Radiation is off and keep all other default values.

c. Press Accept to close the Basic parameters panel.


a. Keep the default Number of iterations and set the Convergence criteria for Energy to 1e-12.

b. Click Accept to close the panel.


a. Input the following for Temperature in the Linear solver group box:

i. Choose W cycle from the Type drop-down list.

ii. Enter 1e-6 for both the Termination criterion and Residual reduction tolerance.

b. Select Double for the solver Precision.

c. Press Accept to close the Advanced solver setup panel.






Go to Solve → Run solution or click on the shortcut button ( ). Start the solver by clicking Start

solution.





1. Once the model has converged, Activate cut.1 if not already activated.

2. Edit cut.1 and make sure that Point and normal is the Set position.

3. Make sure that PX, PY, PZ are 0, 0, and 0.78232, respectively and the NX, NY, and NZ are 0, 0, and 1,

respectively.

4. Press Done and view the model.

The mid-plane temperature distribution shows that the high temperature regions occur at the no-trace

areas and low temperature regions occur at areas with a high trace concentration. This is expected as

the copper content is directly proportional to the trace concentration. It is worth noting that if a compact

or detailed PCB were used in lieu of the traced PCB, one would obtain a fixed temperature for the entire

mid-plane and this fixed temperature would be different from the average temperature of the traced

PCB on the same plane.

Figure 17.7 Temperature Distribution on the PCB (mid-plane)

Note

The spatially varying non-uniform conductivity of the board can also be viewed during post

processing. The conductivities in the three direction K_X, K_Y, and K_Z are available as post-

processing variables with plane cuts and object faces. Figure 17.8 (p. 279) plots kx at the board

mid-plane by selecting K_X from the Contours of drop-down list from Plane cut contours

panel of the cut.1 object. In the present case, because we chose not to model the layers

separately, there will be no variation of the conductivities in the board-normal direction.



Figure 17.8 K_X Distribution on the PCB (mid-plane)

17.12. PCB With the Actual Components Under Forced Convection

Follow these steps for a model that has components:


1. In order to put the actual components back into the model, highlight all the components under the

Inactive folder and drag them back into the Model folder. Highlight the two wall objects created for

the “conduction only" model and drag them into the Inactive folder.

2. Click on the Cabinet and Autoscale it from the Edit window.

3. If not already defined, assign an X Velocity of -1.5 m/s in the Properties tab of the Openings panel

for the Max x side of the cabinet (the minus sign shows that the flow is in the negative x direction).




While not shown here, the trace import feature has a number of advantages on the meshing side.

It should be remembered that detailed PCB's cannot intersect non-conformal assemblies; however,

there is no such limitation for block objects. Since a PCB is represented as a block in the case of

importing traces, non-conformal assemblies can intersect it.

4. Open the Mesh control panel and choose X, Y, Z sizes as 9.5, 7, and 0.7 mm respectively.

5. Keep all other defaults and Generate the mesh.

17.14. Step 2: Set Physical and Numerical Values

1. Since we now have forced convection, go to Problem Setup → Basic parameters toggle on

the Flow button. Keep and choose Turbulent and Zero equation for the flow regime and press Accept

to close the panel.

2. Go to Solution settings → Basic settings and make sure the Number of iterations is 300 and

that the Convergence criteria are the same as the last mode, and press Accept to close the panel.

3. Keep the same Advanced settings as the previous case.


Click Solve → Run Solution to display the Solve panel. Enter a different solution id for the forced

convection model (i.e., A11-conv). Enable Sequential solution of flow and energy equations and click

Start solution.


To display contours of temperature on the board, follow the procedures below.

1. Once the model has converged, deactivate cut.1 and go to Post → Object Face.

2. Select BOARD_OUTLINE.1 from the Object drop-down list, and deselect all the options except Max

Z in the Object sides group box.

3. Turn on the show contours and click on Parameters button.

4. Keep the default selection of Temperature.

5. For Color levels, select This object from the drop-down list.

6. Press Done in the Object face contours panel and then the Object face panel to view the postpro-

cessing object.

This shows the temperature distribution at the top of the surface of the board (Figure 17.9 (p. 281)).

There are two hot spots underneath the high heat flux components.



Figure 17.9 Top Surface Temperature Distribution: PCB With Imported Traces (100

x 100) in Forced Convection

7. Deactivate the face.1 postprocessing object.

17.17. Using the Model Layers Separately Option

Next we revisit the conduction only model. This time all the metal layers will be modeled separately

and not lumped together in the thickness direction.

1. Go to the Post → Load solution ID.

2. Select the solution ID corresponding to the model which has just the PCB without any components.

3. Deactivate all postprocessing objects if any are active.

4. Display the Board layer and via information panel by selecting Trace layers and vias from the

Geometry tab of the Blocks panel for the BOARD_OUTLINE.1 object.

5. Check the Model layers separately box and press Accept to close the panel.

6. Press Done to close the Blocks panel.

Note

• The Model layers separately option automatically creates contact resistance plates in

the plane of the board at the start and end locations of each metal layer. These dummy

plates have zero thermal resistance and their sole purpose is to ensure proper mesh

resolution within the board. Figure 17.10 (p. 282) shows the plates created for the tracing

layers on this board.

• To model each of the layers separately we need to ensure that there is at least one cell

across each of the metal and dielectric layers at the correct locations in the board-normal

direction.



Using the Model Layers Separately Option

Figure 17.10 Contact Resistance Plates for Meshing the Individual Layers Separately

7. Now the model can be meshed again same mesh settings as earlier except for the Minimum gap in

the Z direction, which should be set to 0.25 mm to account for the contact resistance plates, and

solved with the exact same boundary conditions. The temperature distribution and conductivity profiles

on the board can be viewed again during post processing to examine the effect of modeling the layers

separately as compared to the previous case.

17.18. Summary

In this tutorial, you imported the board layout and trace files. Then you simulated the board using a

conduction only model. Postprocessing this model showed high temperature regions occurring at the

no-trace areas and low temperature regions occurring at areas with a high trace concentration. Then

you simulated the board with the components put back into the model and simulated under forced

convection. Then you simulated the conduction using the Model layers separately option.

17.19. Additional Exercise 1

Using this model, you can determine the joule/trace heating of the imported traces. This problem is

described in Tutorial "Joule/Trace Heating".

17.20. Additional Exercise 2

Create a model with a detailed package with thermal solder balls. Place it on a board modeled without

and with separate meshing of the layers and check the difference of temperature distribution.



Chapter 18: Joule/Trace Heating

18.1. Introduction

In Tutorial Trace Layer Import for Printed Circuit Boards (p. 267), you learned how to import a trace layout

of a typical PCB using TCB format and also learned how to model the trace layers separately for better

modeling accuracy. In this tutorial, you will learn how to model resistive heating or joule heating of the

imported traces in the PCB.

Since PCB traces have electrical resistance, they will heat up as current flows through them. Modeling

this phenomenon will provide us with an accurate prediction of the temperature distribution in the

PCB, which can be important, for example, in evaluating the performance of the cooling system.

18.2. Prerequisites

This tutorial assumes that you have completed Tutorial Trace Layer Import for Printed Circuit Boards (p. 267)

of this guide. This same model is used to determine the joule/trace heating capability in ANSYS Icepak.


The model in Tutorial Trace Layer Import for Printed Circuit Boards (p. 267) contains imported traces and

will be used in this tutorial. You will determine the joule/trace heating capacity of the traces.


1. Start ANSYS Icepak, as described in Chapter 1 of the User's Guide.

Note

When ANSYS Icepak starts, the Welcome to Icepak panel will open automatically.

2. Click Unpack in the Welcome to Icepak panel to start a new ANSYS Icepak project.

Note

The File selection panel will appear.

3. In the File selection panel, select the packed project file joule-heating.tzr and click Open.

Note

The project file can be found in your installation directory at ICEPAK_ROOT/tutori-als/joule-heating/joule-heating.tzr .



4. In the Location for the unpacked project panel, select a directory where you would like to place

the packed project file, enter a project name in the New Project text field, and click Unpack.


This tutorial uses an existing model. Since the traces are already imported in the model, you will work

directly on the Joule heating capability in ANSYS Icepak.

1. Select BOARD_OUTLINE.1 from the Model tree and open the Blocks panel.

a. In the Geometry tab, click on the Edit button next to Model trace heating. The Trace heating

panel opens.

i. In the drop-down list under Layers, select INT1_3. The list below Display traces shows

available traces. You can filter the traces to view by setting an Area filter (the default in

ANSYS Icepak is 20% of the Largest trace area) and clicking the Filter button. In this example,

use an Area filter of 17890 mm2, as this will only show the significant traces.

Note

The Trace heating panel lists the traces in each layer in order of descending

area, see Figure 18.1 (p. 285).

ii. Before you create a solid trace of Trace 1_1724 , you need to modify the Max angle filter

and the Min length filter to ignore the fine details in the trace geometry and reduce the

mesh count. If not already selected, select Trace 1_1724 and set the Max angle filter to

135 and the Min length filter to 1.0 mm.



Figure 18.1 Trace Heating Panel Selection and Options

iii. Click on the Create solid trace button. ANSYS Icepak will create a polygonal solid block

named BOARD_OUTLINE.layer-3-trace-1_1724 that contains the trace information.

(The actual name may vary). Click Done to close the Trace heating panel.

Note

You can try reducing the Area filter to 1000 mm2 to check how many traces

appear. We are interested in the second largest trace, trace 1_1724.

b. Click Done in the Blocks panel to close the panel and view the model.

2. Select the polygonal trace from the Model tree and open the Blocks panel.

a. In the Geometry tab of the Blocks panel, make sure there are around 60 vertices for the trace,

as shown in Figure 18.2 (p. 286).




Figure 18.2 Polygonal Trace Block

b. Go to the Properties tab.

i. Make sure that the Solid material is tr_1_1724_sol_mat and then select Edit definition

in the drop-down list.

A. The Materials panel opens.

B. Make sure the Properties tab of the Materials panel looks like Figure 18.3 (p. 287).

C. Press Done to close the Materials panel.



Figure 18.3 Trace Materials Panel Properties Tab

ii. In order to activate Joule heating of the trace, press the Edit button for the Joule option.

The Joule heating power panel opens.

A. For the first boundary condition in the Boundary conditions group box, set Side to

side1, Boundary type to current, and specify the Current to 25 Amps.

B. For the second boundary condition, set Side to side42, Boundary type to voltage, and

the Voltage to 0 V.




Figure 18.4 Boundary conditions for the Trace Block

Note

Current conservation needs to be manually inspected by the user.



Figure 18.5 Entry and Exit Sides for the Trace Block

Note

The side numbers are estimates as they may be slightly different for each

model.

C. Press Done in the Joule heating power panel and then the Blocks panel to close the

panels and view the model.


1. Create a non-conformal assembly for the trace.

a. Right click the BOARD_OUTLINE.1.layer-3-trace-1_1724 object and go to Create and

then Assembly.

b. Double click the assembly you created to open the Assemblies panel.

i. In the Meshing tab, select Mesh separately and input the Slack settings, Mesh type, Max

element size, and Min gap settings as shown in Figure 18.6 (p. 290).




Figure 18.6 Mesh Settings for the Trace Board

Note

Ensure Mesh type is Mesher-HD.



a. Make sure the Mesh type is Mesher-HD.

b. Keep the global settings under the Max element size group box as 9, 5, and 0.75 mm, for X, Y,

and Z respectively.

c. Set the Minimum gap as 0.75, 0.45, and 0.035 mm for X, Y, and Z, respectively.

d. Generate the mesh.

e. Check the mesh quality for the trace and the overall model from the Display and Quality tabs.


1. Double click the cabinet_default_side_maxx object in the Model tree to open the Openings

panel.

a. In the Properties tab, make sure the X Velocity is -1.5 m/s.





a. Since this is a forced convection problem, ensure that the Flow is toggled on and that Turbulent

is selected under Flow regime. Select Zero equation as the turbulence model.

b. Press Accept to close the panel.


a. Make sure the Convergence criteria for Flow is 0.001.

b. Set the Number of iterations to 200 and the Convergence criteria for Energy and Joule heating

to 1e-8.

c. Press Accept to close the panel.



i. Choose W cycle from the Type drop-down list.


b. Make sure the Precision for the solver is Double.

c. Press Accept to close the Advanced solver setup panel.




File → Save Project


1. Click Solve → Run Solution.

2. Click Start solution.


Once the model has converged, create an object face.

1. Select the trace and show the temperature contours.

a. Go to Post → Object face.

b. In the Object drop-down list, select the trace (BOARD_OUTLINE.1.layer-3-trace-1_1724).

c. Select Show contours and click Parameters. In the Object face contours panel, select Temper-

ature in the Contours of drop-down list and select This object next to Calculated in the Color

levels group box. Click Apply.

d. Observe the trend of the temperature contour and how it varies from one side to other, and

compare the maximum temperature for the cases with and without trace modeling (Figure

18.7 (p. 292)).




Figure 18.7 Trace Temperature Contours with Forced Convection

2. Now plot the electric potential of the same trace, Figure 18.8 (p. 293).



Figure 18.8 Trace Electric Potential Contours with Forced Convection

a. Click on Parameters to open the Object face contours panel.

b. Select Electric Potential from the Contours of drop-down list and press Apply.

c. Observe the contours.

• Do you observe any similarity between the temperature and the electric potential contours?




• The temperature contours are closely related to the electric potential contours, which is a

direct result of joule heating of the trace.

d. Press Done in the Object face contours and Object face panels to close the panels.


Tutorial Trace Layer Import for Printed Circuit Boards (p. 267) is utilized to model the joule heating capab-

ility of a trace.



Chapter 19: Microelectronics Packages - Compact models

19.1. Introduction

This tutorial is a case study of a board design. A card supplier is making two package type changes to

an existing commercial board. The objective of the thermal simulation project is to see if the selected

new packages are likely to function without overheating. In the event of over heating, what kind of

thermal management should be recommended?


• Perform a board level simulation with appropriate package models.

• Determine if the selected new packages can function without overheating.

19.2. Prerequisites

This tutorial assumes that you have worked on Sample Session in the Icepak User's Guide and the first

two ANSYS Icepak tutorials of this guide.


A designer is to select packages for a new design at the drawing board level. Available information

about the board and packages is given. Determine cooling solutions in the event there is overheating.





1. Copy the file ICEPAK_ROOT/tutorials/compact-package/compact-package-model-ing.tzr to your working directory. You must replace ICEPAK_ROOT by the full path name of the

directory where ANSYS Icepak is installed on your computer system.



4. In the File selection panel, select the packed project file compact-package-modeling.tzr and

click Open.


like to place the packed project file, enter a project name (i.e., test-1 ) in the New project text field

then click Unpack.


This tutorial uses an existing model. ANSYS Icepak will display the model in the graphics window as

shown in Figure 19.2 (p. 297). Available information about the board and packages is shown in

Table 19.1: Available Details for Objects in the Model (p. 297) and Table 19.2: Available Information for 400

PBGA (p. 298).



Figure 19.2 Layout of the board to be analyzed

Table 19.1 Available Details for Objects in the Model

Power (w)Available information# of Occur-

rences in

model

Object

01.6 mm thick, FR4 Material, six 1 oz. lay-

ers of Copper, 30% coverage for all lay-

ers

1PCB

0Extruded Aluminum3Heat Spreader for TO-220 pack-

ages

1.5� �� = 2.5° C/W

9TO-220 Packages

0.5None6DIP

2.0See Table 19.2: Available Information for

400 PBGA

6400 PBGA (new package type to

the existing board)

3.5232 leads, 40 mm X 40 mm Footprint, 2

mm height

2232 PQFP (new package type to

the existing board)




Note

An ounce of Copper is actually the thickness of 1 ounce/sq.ft of plane copper sheet. Using

copper density this translates to a thickness of 0.035 mm.

Table 19.2 Available Information for 400 PBGA

Where to input this

info?

Other infoMaterial/Con-

ductivity (W/mK)

Size (mm)Feature

Dimensions tab26 x 26 x 2.15Overall package

Die/Mold tab0.8Mold compound

Die/Mold tabSilicon material18 x 18 x 0.4Die

Die/Mold tab80.0 (effective)18 x 18 x 0.035

(equivalent)

Die Flag

Die/Mold tabNot mentioned0.05 mm thickDie Attach

Substrate tabFR40.4 mm thickSubstrate

Substrate tab4 layers, top and

bottom 30% cover-

Copper0.035 mm thickSubstrate traces

age intermediate

layers are 100%

(plane layers)

Substrate tab (use 0

for vias)

Number of vias un-

known

Not mentionedUnknownVias

Solder tab20 x 20 count, full

array

SolderStandardSolder Balls

Die/Mold tabUsually GoldNot mentionedWire Bonds

1. Create the PCB

Create a PCB object by clicking on the Create printed circuit boards button ( ). Then edit the

PCB by clicking the Edit object button ( ) while the PCB object is selected in the Model tree.

Enter the following in the Geometry tab:

Global Coordinates (m)

XS— YS— ZS— XE— YE— ZE

Shape/Type/PlaneNameObject type

0.0 — 0.0 — 0.0— 0.25— NA— 0.2XZpcb.1PCB

a. Go to the Properties tab. Enter the PCB thickness of 1.6 mm for Substrate thickness.

b. Change the default unit from micron to Cu-oz/ft2 for high and low surface thickness and for in-

ternal layer thickness under Trace layer parameters section.

2. Material information for the PCB is in Table 19.1: Available Details for Objects in the Model (p. 297). This

information can be entered for the selected PCB object as shown in Figure 19.3 (p. 299).



Figure 19.3 PCB Edit Form with input based on PCB information in the Table with

Model Object Details above

Now, you should see the PCB object overlapping the block called PCB. There is no more need for

this block.

Note

You recreated the PCB object geometry using coordinates of the imported PCB block.

3. Deactivate the block named “PCB".

4. Heat spreader for TO-220 devices

a. Since default solid material happens to be extruded aluminum, all three spreaders should have

come into the model with correct material specification. Check this information by editing the

objects.

5. Modeling Packages

This model has four different types of objects. Based on available information and our objectives,

we shall use different compact package modeling capabilities in ANSYS Icepak.




a. TO220 Type Packages

i. There are 9 TO-220 device blocks. Select them all at once by drawing a “window" with

Shift+left mouse (see Figure 19.4 (p. 300)). Press Shift+I for an isometric view. Simultaneous

selection can also be done in the Model manager window, press the Ctrl key and left mouse

click to select objects.

Figure 19.4 Window Selecting Multiple Objects for Simultaneous Edit

ii. You should see all TO-220 devices highlighted in the tree. Please note that only TO-220

objects should be selected. If you see other objects highlighted (such as the Spreader objects),

please deselect them by holding down the Ctrl key and left mouse clicking them in the tree.

You can simultaneously edit all of the remaining objects at once by clicking your right mouse

on any one of the selected TO-220 objects in the tree.

A. Select Network for the Block type.

B. Keep the default selection of Two Resistor for the Network type.

C. In order to assign the resistance, we need to identify a reference side. This is the purpose

of “board side" input. We want the resistance to be applied from Junction to the side in

contact with the spreader (Max Z side). We can accomplish this in two ways:

• Designate Min Z side as the Board side and assign the supplier provided resistance

value (2.5 C/W from Table 19.1: Available Details for Objects in the Model (p. 297)) to

Rjc.

OR

• Designate Max Z side as the Board side and assign the supplier provided resistance

value to Rjb.



Note

Zero resistance means that there would not be any link and the res-

istance values are infinite.

D. Input 1.5 W for the Junction power.

Figure 19.5 TO-220 Properties Tab

iii. Click Done to finish the operation.

b. DIP type packages

i. As we did before for the TO_220 objects, select all the DIP objects and simultaneously edit

them.

ii. Use default solid material (any material will work because we are not interested in DIP tem-

perature).

A. Input 0.5 W in the Total Power field.

B. Click Done




Note

Dip is the package type for which we have the least information. So we

are left with two options:

• Try to get information from supplier.

OR

• Perform a tentative simulation with available information. The options are

considered along with the following facts:

– The DIPs constitute a lower heat flux than the other components in

the board.

– This is an existing design in which the DIPs have been known to run

well below their specified temperature even at max power.

Based on the above reasoning, it is easier to perform a tentative simula-

tion with the available power information than to obtain the information

from the supplier. In this context the purpose of the DIP package mod-

eling is to appropriately account for air and PCB heating due to flow over

the DIPs. Accurate prediction of the DIP temperature is not an objective.

c. PQFP package modeling

Internal details are unavailable for the PQFP type package. But based on the exterior details

such as lead count, foot print size, and package height information, it is possible to construct

a compact model of a typical package for screening analysis.

i. Go to the Libraries node by clicking the Library tab in the Model manager window. Then

right-click Libraries and select Search packages.

Note

A package may also be created using either IC package macros or a package

object.)

ii. In the Search package library panel enter all known information about the package

(Table 19.1: Available Details for Objects in the Model (p. 297)) as search criteria. Clicking the

Search button should return 1 the closest matching packages from the library. Pick the

package that is most similar in description to the 232-lead PQFP information available and

select Create. Figure 19.6 (p. 303) depicts the package search procedure.

1If search does not return a relevant package, click on the package object icon to create a new package object. After entering the

few known values, you may enter reasonable values or leave the remaining parameters as defaults.



Figure 19.6 Package Search Procedure

iii. Go back to the Project tab and edit the created package object. Make sure that:

• The Package type is QFP.

• The Package thickness is 2.0 mm.

• The Model type is Compact Conduction Model (CCM).

• The Symmetry is Full.




Note

CCM is a compact model based on geometric simplifications that still preserve

the original heat transfer pathways of the package. It has been demonstrated2 that CCM is fairly accurate and boundary condition independent. Other op-

tions under Model type are:

• To model the package in full detail. This option is meant for package level

modeling. Using this in board or system design will unduly complicate the

simulation.

• To characterize Junction-to-case and Junction-to-board network resistances

for a two resistance compact model. We will be doing this for the PBGA pack-

age.

iv. Select the Die/Mold tab. (The Substrate and Solder tabs show blank interface since QFP

type packages do not have solder or substrate). Enter 3.5 W for Power.

v. Use all other defaults under Die/Mold tab. Click Done to close the tab.

vi. The package created is in an arbitrary location. You may use the Align face centers button

( ) to position the base center of the created package object with that of the 232PQFP

block. The dimensions of the package should match the dimensions of the 232PQFP block:

vii. There is no more need for the 232PQFP block. Deactivate it.

viii. There is another “232PQFP" block (232PQFP.1). Create a copy of the first package object and

align with the remaining “232PQFP" block. Then, deactivate the second “232PQFP" block

(232PQFP.1). The dimensions of the second package should be:

d. PBGA package modeling

We have fairly comprehensive information about the PBGA type package from the supplier

(see Table 19.2: Available Information for 400 PBGA (p. 298)). Using this information we can

construct a CCM or characterize to determine Θjc and Θjb to model it as a 2-resistor network

model as shown here:

i. Select all the blocks named 400-PBGA and edit all of them simultaneously.

A. Select Network as the Block type and Two resistor as the Network type.

B. Set the board side as Min Y.

2Karimanal, K.V. and Refai-Ahmed, G., “Validation of Compact Conduction Models of BGA Under An Expanded Boundary Condition

Set", Proceedings of the ITHERM 2002, May 2002, San Diego, Ca, USA.



C. Input the estimated Θjc (1.4 C/W) and Θjb (6.75 C/W) values in the Rjc and Rjb fields

respectively.

D. Input a Junction power of 2.0 W.

E. Click Done to finish.

ii. Edit the Cabinet. In the Properties tab, you have the option to define the boundary condition

(Wall type) for each side of the cabinet. Set the Wall type for Min x and Max x as Opening.

iii. Press Edit for the Min x side to open the Openings panel.

iv. In the Properties tab of the Openings panel, assign an X velocity of 1 m/s.

v. Click Done to close the Openings panel.

vi. The Max x side opening should have the default settings (free opening).

vii. All other cabinet boundaries should be Default.

viii. Click Done in the Cabinet panel to confirm changes.

ix. You should see the openings on the min and max X sides of the cabinet.


1. Click the mesh icon .




Make sure Hexa unstructured is selected as the Mesh type and Normal is selected for Mesh

parameters.

a.

b. Click Generate to create the mesh.

Figure 19.7 Mesh control panel

c. Evaluate your mesh from the Display and Quality tabs.

2. (optional) Create non-conformal assemblies around each package set to reduce the mesh count. As a

start, use 3 mm slack values for all sides of each assembly. Resize the assemblies if required. With non-

conformal assemblies, it is possible to reduce the number of elements in the mesh significantly. Display

and compare the conformal and non-conformal meshes.


Let us solve the board model with a 1 m/s inlet velocity.

1. Go to Problem setup → Basic parameters and set the Flow regime to Turbulent in the

General setup tab.

Press Accept to close the panel.



2. Go to Solution settings → Basic settings panel and click Reset. It is advisable to always click

the reset button in the Basic settings panel before starting the solver. Set the number of iterations

to 200 in the Basic settings panel and close the panel. Then go to Solution settings → Ad-

vanced settings to open the Advanced solver setup panel. Note that in the Advanced solver setup

panel, under the Linear solver, the solver inputs for temperature have changed.


Save the model after the model building and meshing is complete.



1. Define point monitors of temperature for 232-Lead_PQFP package and DIP objects. A point monitor

will be created to monitor the temperature change with iterations (Figure 19.8 (p. 308)).




Figure 19.8 Monitor Point Definition

2. Go to Solve → Run solution and enable Sequential solution of flow and energy equations.



Figure 19.9 Solve panel



First we would like to get an idea of the general temperature distribution pattern on the board.

1. Create temperature contours of the PCB by clicking the Object face icon ( ), selecting Show contours,

clicking Parameters and selecting This object for the Calculated drop-down list.

• Probe temperatures values at desired location after clicking on probe icon ( ).

• Note the higher temperatures in the parts of the PCB under the PQFP packages.

2. Go to Report → Network block values. The Message window lists all network block temperatures.

Network junction temperatures can also be obtained from the overview report.

3. The closeness of the PBGAs to each other is a cause for their overheating. How much is the problem

due to the temperature of the air approaching these components?

• A picture of the thermal boundary layer over the PBGAs can be seen by taking XY cut plane of

temperature contours over the PBGA blocks.

4. What is the cause for the somewhat high temperatures of the TO-220 devices?




• Are the heat spreaders too close? If so, the air flowing between the spreaders will overheat prevent-

ing further heat dissipation to the air. You can find out if this is the case by creating XZ cut planes

of vectors and contours that cut across the spreader blocks.

5. The highest temperatures are in the 400-PBGA blocks. Effective cooling solutions can be designed by

understanding heat flow pathways.

• Generate a summary report of heat flow for the 400-PBGA blocks. By deactivating the button under

Comb in the summary report panel, you can generate an itemization of heat flow through each

of the sides of the object.


In this tutorial, you performed a board level simulation and determined cooling solutions in the event

there is overheating.


Post-processing showed that the components of 400-PBGA are the most critical object since they are

the hottest. Here are some cooling ideas to set up and perform ANSYS Icepak simulations:

What if...

1. The flow is in the negative X direction?

2. The flow is in the negative X direction, and by judicious use of flow resistances, more flow is diverted

toward the PBGAs (for the same overall flow rate)?

3. The bottom side of the PCB is not dissipating any heat as a result of lying on domain boundary. On

the other hand, there seem to be plenty of space above the board. The main reason for the headroom

above the PCB is the height of the spreader blocks. While there is room to move up the spreader by

a little bit, more room can be gained if the spreader is longer in the X direction but shorter in Y height.

What if both sides of the PCB are exposed to airflow by moving it up?

4. A heatsink is mounted on the PBGA blocks? Will it be possible to use a heatsink in contact with all

PBGAs? Are there any practical issues?



Chapter 20: Multi-Level Meshing

20.1. Objective

The objective of this exercise is to provide a means to improving the mesh resolution and optimizing

the mesh count of a model consisting of CAD objects using the multi-level meshing technique. The

procedure from this exercise should help you make appropriate modeling and meshing choices during

your thermal modeling project.

20.2. Prerequisites

The trainee should be familiar with:

• ANSYS Icepak modeling objects

• Basics of meshing


20.3. Skills Covered

• Basic meshing techniques


• Multi-level meshing

• Uniform mesh parameters option

20.4. Training Method Used

A model with potential for improvement is provided. Then, an approach for improving the model is

presented. Feel free to explore the software interface, collaborate with another trainee, or ask a Tech-

nical Services Engineer.

20.5. Loading the Model

• Unpack and load the model named “HangingNode.tzr"

• Rename it to any other name of your choice.

20.6. Step-by-Step Approach

Without making any changes, the model results in about 650000 finite volume cells. Please note that

this mesh count has been obtained making use of the non-conformal meshing technique that allows

for localized fine meshing, thus eliminating mesh bleeding. However, this mesh does not fully resolve

the fine-level geometric features of the CAD objects. It is possible to further reduce the mesh count

and improve mesh resolution on and around the CAD objects using the multi-level meshing technique.

This procedure starts with a coarse background mesh and resolves fine level features through a series

of successive mesh refinements. It is possible to reduce the mesh count to approximately 500000 and



improve mesh resolution at the same time using this technique along with the uniform mesh parameters

option.

• Generate mesh without modifying the model. You will see a mesh count of about 650,000 cells.

Note

The mesh count may differ slightly on different machines.



Figure 20.1 Mesh of Flow Guide Without Multi-Level Meshing



Step-by-Step Approach

Figure 20.2 Mesh of Sheetmetal_HS Without Multi-Level Meshing

20.7. Modification 1: Multi-Level Meshing of the Fan_Guide

• In the Meshing tab of the fan_guide.1 assembly, retain the slack and minimum gap values. However,

change the Max element size values to 4.0 mm.

• Toggle on Set uniform mesh params.

• In the Multi-level tab, toggle on Allow multi-level meshing and set Max Levels to 2.

• Keep the default selection of Proximity and Curvature.



20.8. Modification 2: Multi-Level Mesh of the Sheetmetal_hs_assy.1

• In the Meshing tab of the Sheetmetal_hs_assy.1 , retain the slack and minimum gap values.

However, change the Max element size values to 3.5 mm.

• Toggle on Set uniform mesh params.

• In the Multi-level tab, toggle on Allow multi-level meshing and keep Max Levels as 2.

• Keep the default selection of Proximity and Curvature.

• Enter a value of 1 for Mesh buffer layers.



Modification 2: Multi-Level Mesh of the Sheetmetal_hs_assy.1

20.9. Generate a Mesh

• Generate a mesh with the modifications using the same settings as before.



• Observe the decrease in element count.

• Display the mesh of the FLOW_GUIDE and the sheetmetal_hs_assy.1 .

Figure 20.3 (p. 318) shows the surface mesh on the flow_guide. Fine mesh resolution in some regions

is necessary for a body fitted mesh. This can be clearly seen in the figure. In addition, it can be

observed that the mesh resolution is coarser in regions where a fine resolution is not necessary to

describe the geometry accurately.

Figure 20.4 (p. 318) shows the mesh on and around the sheetmetal heatsink. It can be seen that the

mesh resolution is fine in the fin region and coarser as we move away from the heatsink.



Generate a Mesh

Figure 20.3 Flow_Guide Mesh

Figure 20.4 Sheetmetal Heatsink Mesh



20.10. Conclusion

Using multi-level meshing, we were able to improve the mesh resolution and instantly transition to

coarser meshes thus reducing the overall mesh count. Hence, this approach significantly reduces run

time while enhancing the accuracy of the simulation.



Conclusion

Chapter 21: Characterizing a BGA-package by Utilizing ECAD Files

21.1. Introduction

In Tutorials "Trace Layer Import for Printed Circuit Boards" and "Joule/Trace Heating" you learned how

to import trace layouts for a PCB. In this tutorial, you will learn how to import trace layouts on a BGA

package substrate by using TCB files.


• Import trace layout of a BGA package substrate in TCB format.

• Display traces using the Color by trace option.

• Plot temperature contours on the wirebonds.

• Determine junction-to-case resistance for the package.

21.2. Prerequisites


solved or read the tutorial "Finned Heat Sink" of this guide.


In this tutorial, you will see how to determine temperature profiles on the wirebonds of a BGA package

and junction-to-case resistance.




3. Specify a name for your project (i.e., BGA-package) and click Create.


To build the model, you will change the units, create the PCB, import the traces and resize the cabinet

to its proper size. Then you will create a wall object.

1. Change the unit of length to mm.

Edit → Preferences

a. In the Preferences panel, click on Units, under the Defaults node. In the Category box, scroll

down and select Length, and under Units, select mm.

b. Click Set as default, Set all to defaults and then This project.

2. Create the package object.



a. Click on the packages object button ( ) in the objects toolbar.

b. In the Packages panel, click the Dimensions tab and select ASCII TCB from the Import ECAD

file drop-down list.

Figure 21.1 The Packages Panel (Dimensions Tab)

c. Select block_1.tcb in the Trace file panel and click Open.

Note

block_1.tcb can be found in the installation directory at ICEPAK_ROOT/tu-torials/BGA-package/block_1.tcb .

d. Keep the numbers for the layers and vias and click Accept in the Board layer and via information

panel.

e. Click on the Die/Mold tab and assign a die Power of 0.5 W.

f. Click Done.

g. Click on the Cabinet in the object tree and click the Autoscale button located in the edit window

in the lower right corner of the main menu.



Note

Click the Scale to fit icon ( ) to refocus your model.

h. Right click on the package object in the object tree, choose Traces → Color by trace to display

the traces.

Figure 21.2 Display of Traces

As can be seen in Figure 21.2 (p. 323), the wirebonds are lumped into polygonal plates by

ANSYS Icepak.

i. Change the cabinet zS to -1.2 mm.

j. Create a PCB object and input the following in the Geometry tab:

Start / endSpecify byX-YPlane

7.03 mmxE-7.03 mmxS

7.03 mmyE-7.03 mmyS

—zE-1.2 mmzS

k. In the Properties tab, set the substrate thickness as 0.8 mm, then enter the following Cu percent-

ages for the layers:




Figure 21.3 Properties Tab of the Printed Circuit Boards Panel

l. Click on Update. Note that the thermal conductivity information (plane and normal) for the PCB

is updated.

m. Press Done to close the panel.

n. Create a wall object and align it with the min-z side of the cabinet and Rename it as Bottom.

o. Edit the wall object and insulate it by keeping the heat flux as zero in the Properties tab.

p. Make a copy of the wall and translate it in the z direction by 2.95 mm and rename the new wall

to Top.

We would like to determine the heat transfer coefficient on the top surface with the well-

known correlation in the literature, (Incropera et. al 1). In order to do that, you can follow the

procedure in Figure 21.4 (p. 325).

1Frank Incropera and David DeWitt, Fundamentals of Heat and Mass Transfer, John Wiley & Sons, Inc., New York, 1981.



Figure 21.4 Determining Heat Transfer Coefficient on the Top Wall


1. Click the Generate mesh button ( ).

2. In the Mesh control panel, enter 0.5 mm, 0.5 mm, and 0.14 mm for the Max element size for x, y,

and z, respectively. Change the Minimum gap values to 0.05 mm, 0.05 mm, and 0.01 mm for x, y and

z, respectively. In the Misc tab, unselect Allow minimum gap changes and click Change value and

mesh in the Minimum separation panels.

Note

Ensure that Mesh type is Mesher-HD.




3. Click Generate.

Figure 21.5 Mesh control Panel

4. Click Close to close the panel once you have created the mesh.



a. Uncheck Flow in the General setup tab.

b. Turn off the radiation and click Accept to close the panel.


a. Change the Number of iterations to 25 and the Convergence criteria for Energy to 1e-15.

b. Click Accept to close the panel.



i. Choose W from the Type drop-down list.


b. In the Precision drop-down list, select Double.

c. Click Accept to save your settings and close the panel.











Go to Solve → Run solution. Click Start solution.


1. When the model converges, plot the temperatures contours on the wirebond and view the variation/sym-

metry of the temperature profiles.

a. Go to Post → Object face and choose the wirebonds under the package object.

Figure 21.6 Object face Panel

b. Select Show contours and click Parameters.

c. Select This object from the Calculated drop-down list.

d. Press Done in the Object face contours and Object face panels to close the panels and view

the temperature contours.




Figure 21.7 Temperature Contours on the Wirebonds (Top View)

2. Go to the Report → Summary report and click on New twice.

a. Choose Source_DIE1 under the package object for the first object and the Top wall for the second

object.

b. Keep the default selection of Temperature under Value for both.

c. Press Write to create the Summary report.

Max die and max top wall temperatures are determined as 142.0 and 129.9°C, respectively. Note

that the top wall represents the case for the package. Therefore, junction-to-case resistance for

this package is determined as:



(21–1)=−

� ��

� �

�

��

Where � is the die power (0.5 W in this case). Therefore,

(21–2)= = °−� ��

��

��


In this tutorial, you learned how to import trace layouts for a PCB on a BGA package substrate by using

a TCB file.



Step 8: Summary

Chapter 22: Zero Slack with Non-Conformal Meshing

22.1. Introduction

This tutorial compares the mesh of a non-conformal assembly with and without slack values around a

heat sink, package and board. The zero slack scenario will be solved and the number of iterations, and

temperature distribution on objects in the model will be performed.

In this tutorial you will learn how to use the zero slack capability in ANSYS Icepak.

22.2. Prerequisites

This tutorial assumes that you have reviewed Sample Session in the Icepak User's Guide and the tutorials

"Finned Heat Sink" and "RF Amplifier" of this guide.


The model consists of a detailed heat sink, a BGA package, a block with traces and fluid blocks. The

model setup is shown in Figure 22.1 (p. 332).



Figure 22.1 Problem Schematic

The objective of this exercise is to illustrate the advantage of using the zero slack capability. The model

will be constructed using the default metric unit system.




1. Copy the file ICEPAK_ROOT/tutorials/ZeroSlack/ZeroSlack_Tut.tzr to your working

directory. You must replace ICEPAK_ROOT by the full path name of the directory where ANSYS Icepak

is installed on your computer system.





4. In the File selection panel, select the packed project file ZeroSlack_Tut.tzr and click Open.



like to place the unpacked project file, enter a project name (e.g.0–slack) in the New project text field

then click Unpack.

22.5. Step 2: Default Units

Make sure the default unit of length is mm.

Edit → Preferences

1. In the Preferences panel, click on Units under the Defaults node. In the Category box, scroll down

and select Length, and under Units, make sure mm has an asterisk next to it. If there is no asterisk

next to mm:

a. Select mm from the Units box.

b. Click Set as default.

2. Click Set all to defaults and click This project.


This tutorial uses an existing model. The model contains existing package, board and heatsink assemblies.

22.7. Step 4: Import Traces

1. In the model tree, expand the Board assembly to display the pcb object if it is not already visible. Right

click pcb in the Model manager window and click Edit to display the Blocks panel.

2. In the Geometry tab, select ASCII TCB from the Import ECAD file drop-down list.

Note

You need to unzip the tcb file before you can import it.

3. In the Trace file panel, select BOARD_OUTLINE.tcb. Turn off the Resize Block option because the pcb

was imported using an idf file, so the dimensions are already correct. This process may take a few

minutes depending on the speed of your computer.



Step 4: Import Traces

Note

The Resize Block option is necessary when the board size is not known or an idf file

is not available.

4. Once the import is completed, you can edit the layer information in the Board layer and via inform-

ation panel. Enter the layer thickness as shown in the table below.

Thickness (mm)Layer

0.04Layer 1

0.45364Layer 2

0.062Layer 3

0.467Layer 4

0.055Layer 5

0.442Layer 6

0.045Layer 7

5. By default, layers are lumped for each sub-grid, therefore, the Model layers separately option is off

and will need to be enabled.

a. Click Accept to close the Board layer and via information panel.

b. Then click Edit next to Trace layers and vias in the Blocks panel to reopen the Board layer and

via information panel.

c. The Model layers separately option can now be enabled.

6. The via information is imported automatically, so keep the default settings.

7. Click Accept to save your settings.

Note

• You can view the traces in three different ways, i.e. Single color, Color by trace, or

Color by layer.

• The meshing plates are placed at the location of the different layers; they are used to

ensure the mesh resolution is high enough at the different layers.

8. Click Done to close the Blocks panel.

22.8. Step 5: Add Slack Values

You will add slack values to the heat sink assembly.

Note

Non-conformal assemblies are used to reduce mesh count in models and to improve mesh

quality.

1. Set the slack values for the heat sink assembly as shown in the figure below.



22.9. Step 6: Generate Mesh (with Slack Values)

You will generate a mesh for the heatsink assembly with slack values.


2. Make sure that the Min elements in gap is 2, the Min elements on edge is 1, and the Max size ratio

is 3.

3. Go to the Local tab and click Edit next to Object params. You will see the following requested values

in the Per-object meshing parameters panel (scroll down to see the inside ratios):

Table 22.1 Object Parameters

RequestedParameterObject nameObject type

25X countpcbblock

5Z count

2all inside ratiosheatsink.1assembly

2all inside ratiosboardassembly

2all inside ratiospackageassembly

4. Press Done to close the Per-object meshing parameters panel.

5. Keep all other settings as default and click Generate.



Step 6: Generate Mesh (with Slack Values)

6. Take note of the mesh count and view a cut plane of the mesh from the Display tab.

Note

The package is not well resolved and it is divided between the heatsink and board as-

semblies. Moreover, mesh bleeding from the meshing plates extends beyond the board

because of the slack values.

22.10. Step 7: Zero Slack

Next, we will consider a board with non-conformal meshing with zero slack values.

Non-conformal assemblies with zero slack help in resolving specific objects without extending the mesh

to the rest of the cabinet. Also, zero slack non-conformal assemblies remove certain limitations that are

present with regular non-conformal assemblies like intersections with other non-conformal assemblies.

In this tutorial, the use of zero slack non-conformal assemblies allows us to have a separate non-con-

formal assembly for the package and to accurately resolve the mesh.

Note

Currently, zero slack assemblies are unable to participate in radiation when a surface coincides

with the assembly interface.

1. Change the slack values for the heat sink assembly as shown in the figure below.



2. In addition, enable Mesh separately in the package and board assemblies (do not change any other

values in these assemblies).

22.11. Step 8: Generate Mesh (with Zero Slack)

Generate a mesh with the same global mesh settings as in Step 6: Generate Mesh (with Slack Values) (p. 335)

so that you can compare the mesh count. Observe that the mesh count is significantly less than that

of the mesh with slack values.


1. In the model tree, go to Solution settings → Basic settings and Solution settings →Advanced settings, and verify that the following values are set:

2. Go to Problem setup → Basic parameters and make sure the Flow regime is Turbulent and

the turbulence model is Zero equation in the General setup tab. Also, give a small initial (global) X

velocity of –1.5 m/s in Transient setup tab. Accept the changes made and exit this window.









Go to Solve → Run solution. Click Start solution.


After the solution has converged, create the following post processing objects:


Plane cut (x-z) view of the velocity

vectors in the y plane.

Set position: Y plane through

center

cut.1

Show vectors

Object-face view of temperature

on pcb

Object: pcbface.1

Note the min & max temperatures

and the temperature distribution.

Show contours / Parameters


Object-face showing the conduct-

ivity, K_X.

Object: pcbface.2

Show contours / Parameters

Contours of : K_X


Zero slack is a feature in ANSYS Icepak that alleviates most restrictions encountered while using the

original non-conformal assemblies. Zero slack non-conformal assemblies not only reduces mesh count

further than original non-conformal assemblies but also allow the user to mesh specific objects separately.

For example in this model, the zero slack capability allowed meshing of the package object separately.



Chapter 23: ANSYS Icepak - ANSYS Workbench IntegrationTutorial

23.1. Introduction

This tutorial demonstrates how to create and solve an ANSYS Icepak analysis in ANSYS Workbench. You

will model a geometry using the direct CAD modeling feature in ANSYS Icepak and create a non-con-

formal mesh for the complex shapes. The project will also include postprocessing the results in ANSYS

CFD-Post and performing a static structural analysis.


• Create an ANSYS Icepak analysis in ANSYS Workbench.

• Postprocess results in ANSYS CFD-Post.

• Solve a project and transfer to ANSYS Mechanical for further analysis.

23.2. Prerequisites

This tutorial assumes that you have little experience with ANSYS Workbench and so each step will be

explicitly described.


The graphics board contains a heat sink with extruded fins having aerofoil cross section, a PCB, capacitors,

memory cards and ports. These objects are placed in a setup as shown in the figure below.



Figure 23.1 Problem Schematic


1. Start ANSYS Workbench.

Note

When ANSYS Workbench starts, the Toolbox and Project Schematic are displayed.




1. Add a Geometry template by dragging the template from the Toolbar under the Component Systems

node into the Project Schematic. Perform a right mouse click on the Geometry cell (A2) and go to

Import Geometry. Click Browse and select graphics_card_simple.stp to load the geometry.

The file graphics_card_simple.stp can be found at ICEPAK_ROOT/tutorials/Workbench .

Note

A green check mark in the Geometry cell indicates the geometry has been imported

successfully.

2. Double-click the Geometry (A2) cell to open DesignModeler as you need to edit the geometry first

before exporting into ANSYS Icepak.

a. Keep the selection of Meter as the desired length unit and press OK.

b. Click Generate to display the model.

c. Edit the geometry in DesignModeler using the Electronics option in the Tools menu. Select

Simplify and choose the appropriate simplification level and select bodies.

i. Select All objects for Selection Filter.

ii. Keep the Simplification Type as Level 2 and click Generate.

Refer to the Design Modeler documentation for more detailed information on using the

Electronics options.

Note

The Electronics menu is shown only if the DesignModeler option Enable Electronics

Options is turned on.




d. Close DesignModeler and return to ANSYS Workbench.

3. Drag and drop an Icepak template into the Project Schematic on top of the Geometry cell (A2) to

transfer the geometry into ANSYS Icepak.

4. Right click on the Setup cell (B2) and select Edit to launch ANSYS Icepak.

a. The CAD model appears in the graphics display window and has been converted into ANSYS

Icepak objects. Click the isometric toolbar icon ( ) to display the isometric view of the model.

b. In the object edit panel of each of the objects, rename the object (if necessary) in the Info tab

and enter the specifications in Properties tab as shown in Table 23.1: Object Properties (p. 342).

Caution

It is recommended to use unique names for Icepak objects when importing from

DesignModeler as objects may be erroneously skipped when re-importing the

model or duplicated when refreshing the geometry.

Note

To open the object edit panel, perform a right mouse click on the object and select

Edit. After editing the object, you can press Update to save the changes and click

a different object in the Model tree to go to that object without closing the panel.

Table 23.1 Object Properties

Total PowerSolid MaterialNew nameObject

0.0 WattsdefaultSERIAL_PORTSERIAL_PORT

5 WattsCeramic_materialMEMORY_1MEMORY1

5 WattsCeramic_materialMEMORY_2MEMORY1.1

0.0 WattsdefaultCAPACITOR_1CAPACITOR

0.0 WattsdefaultCAPACITOR_2CAPACITOR.1

0.0 WattsdefaultKBKB

0.0 WattsdefaultHEAT_SINKHEAT_SINK

20 WattsCeramic_materialCPUCPU

0.0 WattsCustom- PCB solid_material

Conductivity type- Ortho-

tropic

PCBALHPA_MAIN_PCB

X = 20, Y = 0.4, Z = 20

Note

Edit the Solid material by selecting a material in the drop down list. To create a

(Custom) material, select Create material in the drop down list and click the

Properties tab in the Materials panel and enter the specifications.



c. Resize edit the properties of the default cabinet in the Cabinet panel.

Model → Cabinet

i. In the Cabinet panel, click the Geometry tab. Under Location, enter the following coordinates:

Table 23.2 Coordinates for the Cabinet

xE = 0.03 mxS = -0.19 m

yE = 0.02848 myS = 0 m

zE = 0 mzS = -0.11 m

ii. Edit the cabinet properties to specify Min x and Max x sides as openings.

A. In the Properties tab of the Cabinet object panel, select Opening from the drop-down

menu under Wall type for Min x and Max x.

B. Select Edit to display the opening for the Max x object panel.

C. In the Properties tab, specify the x velocity to be –2 m/s. Click Done in the Openings

and Cabinet panels to apply the changes and close the panels.

d. The final model should correspond to the one shown below.




Figure 23.2 The Final Model Display


Note

For more information on how to refine a mesh locally, refer to Refining the Mesh Locally in

the Icepak User's Guide.

1. Click the assembly toolbar icon ( ) to create an assembly. Add the HEAT_SINK and CPU objects to

the assembly and rename it CPU_assembly.

Note

To add objects to an assembly, select one or more objects in the Model manager

window and drag them into the desired assembly node.



2. Go to the CPU_assembly object panel and click the Meshing tab. Enable the Mesh separately option

and enter the following slack values. Click Done to close the panel.

Table 23.3 Slack Values

Max X = 0.005 mMin X = 0.005 m

Max Y = 0 mMin Y = 0.0016 m

Max Z = 0.005 mMin Z = 0.001 m

3. Specify the overall mesh controls as shown in the Mesh control panel below.


Note

The Mesh units and Minimum gap values are in mm, and Set uniform mesh params

is checked in the Global tab.

Press Generate to create the mesh. You can check the mesh using the Display and Quality tabs

in the Mesh control panel. Press Close when you are done.





1. Go to Problem setup → Basic parameters in the Model manager window.

a. In the General setup tab, make sure that both flow and the temperature fields are switched on.

b. Select Turbulent and Zero equation for the Flow regime and turn Off the Radiation.

c. Click Accept to close the panel.

2. Go to Solution settings → Basic settings and Solution settings → Advanced settings in

the Model manager window and verify that the following values are set for each variable:

Basic settings

No. of iterations = 100

Flow = 0.001

Energy = 1e-7

Advanced settings

Pressure = 0.3

Momentum = 0.7


1. Go to File → Save project.

Note

You can click the save icon ( ) in the File commands toolbar.

The Save As panel appears.

2. Specify the name ice_wb for your project and click Save.

3. ANSYS Workbench will close ANSYS Icepak to save the model, you will need to launch ANSYS Icepak

again to continue.


1. Go to Solve → Run solution to display the Solve panel.

2. Keep the default settings in the Solve panel.

3. Click Start solution to start the solver.

ANSYS Icepak begins to calculate a solution for the model and a separate window opens where



calculation. Note that the actual values of the residuals may differ slightly on different machines,

so your plot may not look exactly the same as the figure below.



4. Once the solution converges, click Done in the Solution residuals window to close it.

23.10. Step 7: Examine the Results with CFD-Post

Note

The postprocessing of results can be done within ANSYS Icepak; however, you can also ex-

amine results in ANSYS CFD-Post. This section will describe how to transfer information to

ANSYS CFD-Post and use its postprocessing options, so you may close ANSYS Icepak.



Step 7: Examine the Results with CFD-Post

1. After calculating a solution in ANSYS Icepak, a green check mark will be displayed in the Icepak

Solution cell in the Project Schematic. The green check mark indicates that all data is up to date. Select

Results under the Component Systems node in the Toolbox. Drag the Results cell on top of the Icepak

Solution cell (B3) to transfer the data.

2. Double click the C2 Results cell to launch ANSYS CFD-Post. The model should appear in the display

window.

3. To generate contours, please do the following:

a. Go to Insert → Contour or click on the Contour button to create a contour. Retain the name

“Contour 1” and click OK.

b. In the Geometry tab under Details of Contour 1:

i. Keep the default selection of All Domains in the Domains drop-down list.

ii. Click on the ... button next to Locations to display the Locations Selector dialog box.

Highlight all CPU, PCB and HEAT_SINK objects and click OK to close the panel.

Note

You can select multiple objects by holding down either Shift or Ctrl and se-

lecting the objects.

iii. Select Temperature in the Variable drop-down list.

iv. Select Apply to display the contours.

4. To generate a 3D streamline, please do the following:

a. Go to Insert → Streamline or click on the Streamline button to create the streamline. Retain

the name “Streamline 1” and click OK.

b. In the Geometry tab under Details of Streamline 1:

i. Keep the default selection of 3D Streamline in the Type drop-down list.

ii. Keep the default selection of All Domains in the Domains drop-down list.

iii. Select cabinet_default_side_maxx minx from the Start From drop-down list.

iv. Keep the default selection of Velocity in the Variable drop-down list.

v. Keep all other defaults and click Apply to display the streamline.

c. You can also animate the streamline. To animate the streamline, go to Tools → Animation or

click on the animation button .

5. When you are done examining the results, close ANSYS CFD-Post and return to ANSYS Workbench.



23.11. Step 8: Thermo-Mechanical Structural Analysis

In addition to solving this problem in ANSYS Icepak, you can also perform a static structural analysis.

1. Select Static Structural from the Toolbox and drag and drop this cell on top of the Icepak Solution

cell (B3).

2. Click on the Geometry cell (A2) and drag and drop it on top of the Static Structural Geometry cell

(D3). The geometry is now shared.

3. Right click on the Setup cell (D5) and click Update.

4. Double click on the Model cell ( D4) to launch ANSYS Mechanical.

5. Click on the Imported Body Temperature object. This object is found under the Imported Load

(Solution) node.

6. Under Details, ensure that the Scoping Method is Geometry Selection. Click the Box Select button

, hold down the Ctrl key and drag a box around the entire model to select it. Click

on the cell to the right of Geometry and then click Apply. Nine bodies should be selected.

7. Select All from the Icepak Body drop-down list.

8. Click Solve.


In this tutorial, you imported CAD objects and set up a problem. You then created a non-conformal

mesh using the hex-dominant mesher. This forced convection problem was solved for flow and heat

transfer and the results were examined on contours and 3D streamlines in the model.



Step 9: Summary

Chapter 24: Postprocessing Using ANSYS CFD-Post

24.1. Introduction

This tutorial demonstrates the use of ANSYS CFD-Post for post-processing results from ANSYS Icepak

analyses.


• Create a workflow in ANSYS Workbench.

• Postprocess ANSYS Icepak results in ANSYS CFD-Post.

24.2. Prerequisites

• Familiarity with the ANSYS Workbench interface

• Familiarity with the ANSYS Icepak interface

Figure 24.1 Quick Reference - CFD Post Interface



Figure 24.2 Quick Reference - Mouse Button Mapping (default) in CFD Post:

To adjust or view the mouse mapping options, go to Edit → Options, then Viewer Setup → Mouse

Mapping in ANSYS CFD-Post.


Figure 24.3 (p. 352) shows the ANSYS Icepak model of a graphics card that contains a printed circuit

board. The board components include memory cards, capacitors, CPU, and serial connectors for peri-

pheral devices. The CPU is cooled by a heat sink. A fan and grille have been used to enhance the con-

vective heat transfer within the system. Two configurations, varying the positioning of the fan and grille,

will be considered for CFD analysis.

Figure 24.3 Problem Schematic - Graphics Card Model (two configurations)


1. Create a workflow by linking ANSYS Icepak and ANSYS CFD-Post in ANSYS Workbench.

a. Start a new ANSYS Workbench session.



b. Drag an ANSYS Icepak component module from the Toolbox and drop it on the Project

Schematic window as shown in Figure 24.4 (p. 353).

Figure 24.4 Creating an ANSYS Icepak Component

c. Rename the ANSYS Icepak component module as Parametric Setup as shown in Figure

24.5 (p. 353). To rename the title, double click on the title Icepak or click the left mouse button

on the down arrow ( ) and select the Rename option from the drop down list.

Figure 24.5 Renaming the ANSYS Icepak Component Module

d. As shown in Figure 24.6 (p. 354) and Figure 24.7 (p. 354), drag and drop a Results (ANSYS CFD-

Post) component module onto the Solution cell of the Parametric Setup to link the ANSYS Icepak

analysis to ANSYS CFD-Post. Rename the Results component module to CFD Post .



Step 1: Create a New Project

Figure 24.6 Linking the Results (ANSYS CFD-Post) Component to the ANSYS

Icepak Component

Figure 24.7 Final Project Schematic

e. Save the project using File/Save (name the project as ice-cfdpost ) from the ANSYS Workbench

interface.

2. Import project into ANSYS Icepak

a. Right click the ANSYS Icepak Setup cell and import the packed ANSYS Icepak project file ice-cfdpost.tzr located in the project directory.

b. The ANSYS Icepak interface will launch with the selected project loaded for modeling/analysis.

24.5. Step 2: Parametric Trials and Solver Settings

1. Go to Edit → Preferences → Postprocessing and confirm that Merge zones when possible for

CFD-post data option is selected.

2. Go to Solve → Run solution → Results and verify that Create Heat Flux Vector in CFD Post is

enabled and click Dismiss.



3. Go to Solve → Run optimization.

a. In the Design variables tab, review the parametric setup.

b. In the Trials tab, note that two of the four trials will be considered for CFD analysis.

Figure 24.8 Solution Trials


1. Click Run in the Parameters and optimization panel.

2. ANSYS Icepak will run two trials and automatically write out the results for post-processing in ANSYS

CFD-Post at the end of each trial.

3. Save the project by going to File → Save project.

4. Close ANSYS Icepak by going to File → Close Icepak.

24.7. Step 4: Postprocessing Using ANSYS CFD-Post

1. Open the results in ANSYS CFD-Post.

a. On the project schematic, double click the Results cell to launch the ANSYS CFD-Post interface.

b. ANSYS CFD-Post automatically reads in the most recent solution set (trial 004 ).

2. Create a Surface Group for the board and all the components.



Step 4: Postprocessing Using ANSYS CFD-Post

a. Go to Insert → Location → Surface Group.

b. Name the group as BoardANDComponents .

c. Go to the Details view located on the lower left hand side of the screen (see Figure 24.1 (p. 351)).

Figure 24.9 Details View for BoardANDComponents Surface Group

d. In the Geometry tab, click next to Locations to open the Location Selector panel.

i. As shown in Figure 24.10 (p. 356), hold down Shift and the left mouse button to select all but

the last eight (cabinet*, fan and grille) surfaces from the list.

Figure 24.10 Selection for the BoardANDComponents Surface Group

ii. Click OK to close the Location Selector panel and add the surfaces.

e. Click Apply in the Geometry tab to apply the settings.

3. Create another Surface Group for the cabinet.

a. Go to Insert → Location → Surface Group and name the group CabinetSurfaces .



Figure 24.11 Listing of Surface Groups under User Locations and Plots

b. As before, open the Location Selector panel, but this time select only the cabinet surfaces, and

press OK.

Figure 24.12 Selection for the CabinetSurfaces Surface Group

c. In the Render tab, apply the settings as shown in Figure 24.13 (p. 358) and click Apply.




Figure 24.13 Rendering Details for the CabinetSurfaces Surface Group

d. Uncheck the BoardANDComponents object from User Locations and Plots.



Figure 24.14 Updated Model

e. Note that these newly create Surface Groups are listed under User Locations and Plots in the

Outline tab.

4. Plot Contours of Temperature on the Surface Group BoardANDComponents .

a. Change the Units for this postprocessing session.

i. Go to Edit → Options → Units.

ii. Set the System to Custom.

iii. Set the unit for Temperature to C.




Figure 24.15 Setting Units in CFD Post

iv. Click Apply and then OK to set the units and close the panel.

b. Go to Insert → Contour and create a new contour object named TemperatureContours .

c. For the contour TemperatureContours , update the settings for the Geometry tab of the

Details view as shown in Figure 24.16 (p. 361) and click Apply.



Figure 24.16 Geometry Settings for TemperatureContours

d. Go to the Render tab and deselect Show contour lines.

e. Click Apply to create the contour.

Note

TemperatureContours is listed under User Locations and Plots.

5. Modify the display of the default legend view.

a. Double click Default Legend View 1 listed under User Locations and Plots to access the corres-

ponding Details view.

b. Modify the settings in the Definitions and the Appearance tabs as shown in Figure 24.17 (p. 362)

and click Apply.




Figure 24.17 Settings for Default Legend View 1

Figure 24.18 Modified Legend View

6. Plot Vectors, displaying heat flux on the Surface Group BoardANDComponents .



a. Deselect TemperatureContours in the User Locations and Plots node.

b. Go to Insert → Vector and create a new Vector object named HeatFluxVectors and click

OK.

c. Modify the Geometry tab of the Details view as shown in Figure 24.19 (p. 363) and click Apply.

Figure 24.19 Geometry Settings for HeatFluxVectors

Figure 24.20 Display of HeatFluxVectors

7. Plot Thermal Chokepoint, displaying regions of high heat flux on the Surface Group BoardANDCom-ponents .

a. Deselect HeatFluxVectors in the User Locations and Plots node.




b. Go to Insert → Contour and create a new Contour object named Chokepoint and click OK.

c. Open the Location Selector panel and select only the ALPHA_MAIN_PCB surfaces. Press OK to

close the Location Selector panel and add the surfaces.

Figure 24.21 Selection for Thermal Chokepoint

d. Modify the Geometry tab of the Details view as shown in Figure 24.22 (p. 365) and click Apply.



Figure 24.22 Geometry Settings for Chokepoint




Figure 24.23 Display of Chokepoint

8. Plot Streamlines originating from the fan and colored by temperature.

a. Deselect Chokepoint and select TemperatureContours in the User Locations and Plots

node.

b. Go to Insert → Streamline and create a new Streamline object named StreamlinesFan and

click OK to access the Details view panel.

c. Modify the Geometry tab as shown in Figure 24.24 (p. 367) and click Apply.



Figure 24.24 Geometry Settings for StreamlinesFan

d. Modify the Color tab as shown in Figure 24.25 (p. 367) and click Apply.

Figure 24.25 Color Settings for StreamlinesFans

e. Modify the Symbol tab as shown in Figure 24.26 (p. 368) and click Apply.




Figure 24.26 Symbol Settings for StreamlinesFan

Figure 24.27 Display of StreamlinesFan

9. Create a Keyframe Animation of StreamlinesFan .

a. Go to Tools → Animation and select Keyframe Animation.

b. Click the button to insert a new frame called KeyframeNo1 as shown in Figure 24.28 (p. 369).



Figure 24.28 Keyframe Animation Panel

c. Right click the background next to the model in the 3D viewer and select the View from +Y option

under Predefined Camera.

Figure 24.29 View From +Y

d. Add another keyframe called KeyframeNo2 to the Animation panel.

e. Check the Animate Camera option on the Keyframe Animation panel (you may need to activate

the display of the lower half of the Animation panel using the drop down arrow ).

f. Similarly, update the display and add new frames as follows:

i. View from -Z and add KeyframeNo3.




ii. View from +X and add KeyframeNo4.

iii. Isometric view (Y up) and add KeyframeNo5.

g. Click to view the animation.

h. Click the Options button on the Animation panel to access the Animation Options panel.

i. Set the Animation Speed to Slower from the drop-down menu by a factor of 20 and click OK.

Figure 24.30 Animation Options Panel

j. Replay the animation and note that the animation is less choppy compared to the original one.

k. Close the Keyframe Animation panel.

l. Deselect the TemperatureContours and StreamlinesFan objects under User Locations

and Plots.

10. Create a Plane object displaying temperature contours and velocity vectors.

a. Go to Insert → Location → Plane and create a plane named PlaneCut .

b. Modify the Details for PlaneCut as shown in Figure 24.31 (p. 371) and click Apply.



Figure 24.31 Details for PlaneCut

c. Deactivate the display of the plane by deselecting PlaneCut and activate the contour display

by selecting TemperatureContours under User Locations and Plots.

d. Double click on TemperatureContours or right click Edit to access the Details view. Update

the details as shown in Figure 24.32 (p. 371) and click Apply.

Figure 24.32 Details for TemperatureContours




Figure 24.33 Display of PlaneCut

e. Go to the Details view for the PlaneCut (do not activate the display of the PlaneCut ) and

make the following modifications:

i. Switch Method to XY Plane and click Apply.

ii. Use the scroll bar to change the Z location for PlaneCut .

f. The plane cut can also be traversed across the domain using the animation tools in CFD Post.

i. Go to Tools → Animation and select Quick Animation (default) and highlight the PlaneCutobject.

ii. Using the scroll bar, adjust the number of frames for the animation as shown in Figure

24.34 (p. 373) and click the button.



Figure 24.34 Quick Animation Settings

iii. The animation can be viewed on the screen or can be written out to an animation file by

checking the Save Movie option.

iv. Stop the animation by clicking the button.

v. Close the Animation panel.

g. Deactivate the display of the contours by deselecting the TemperatureContours object under

User Locations and Plots.

h. Go to Insert → Vector and create a vector object named VelVectors .

i. Modify the Details for VelVectors to set the Location to PlaneCut and click Apply.

j. As before, use the Details view for the PlaneCut to manually traverse the plane displaying the

vectors across the domain.

k. Deactivate the display of the vectors by deselecting Velvectors under User Locations and

Plots.

11. Create an Isosurface of 27°C and 3 m/s.

a. Go to Insert → Location → Isosurface and create an Isosurface name HotSpots .

b. Modify the Details for HotSpots to create an isosurface for 27°C (Variable: Temperature ,

Value: 27°C).

c. Similarly, modify the Details to create an isosurface for 3 m/s (Variable: Velocity , Value: 3m/s).

d. Deactivate the display of the isosurface by deselecting HotSpots under User Locations and

Plots.

12. Create a Volume for values above 25°C.

a. Go to Insert → Location → Volume and create a Volume named IsoVolume .

b. Modify the Details for IsoVolume as shown in Figure 24.35 (p. 374) and click Apply.




Figure 24.35 Details of IsoVolume

Figure 24.36 Display of IsoVolume

c. Deactivate the display of the volume by deselecting IsoVolume under User Locations and

Plots.



13. Create a Chart of Temperature variation across a Line.

a. Go to Insert → Location → Line and create a Line named ForChart .

b. Modify the Details for ForChart as shown in Figure 24.37 (p. 375). and click Apply.

Figure 24.37 Details for Line ForChart

c. Deactivate the display of the line by deselecting ForChart under User Locations and Plots.

d. Go to Insert → Chart to create a Chart named TemperatureVariation .

e. Modify the Details for TemperatureVariation as follows:

i. General tab: Set the Type to XY.

ii. General tab: Set the Title to Temperature Variation along Z axis .

iii. Data Series tab: Set Location to ForChart .

iv. X Axis tab: Set Variable to Z.

v. Y Axis tab: Set Variable to Temperature .

f. Leave all other settings as their defaults and click Apply.




Figure 24.38 Plot of TemperatureVariation Along ForChart

Note

The chart TemperatureVariation is added under the Report node of the

Outline tree.

14. Create an Expression and Variable that can be used for postprocessing.

a. Switch to the Expressions tab (located next to the Outline tab) and review the list of available

expressions.



i. Right click in the white space and click New to create a new expression named VelocityR-atio .

ii. Click Ok to access the Details view for VelocityRatio .

iii. Right click the white space in the Definition tab to access the Functions, Expressions,

Variables, Locations and Constants which will be used to create the expression VelocityR-atio .

iv. Create the expression as shown in Figure 24.39 (p. 377) and click Apply.

Figure 24.39 Expression for VelocityRatio

Note

Velocity is found under Variables, volumeAve()@ is found under Functions

→ CFDPost, and default_fluid is found under Locations → Other.




b. Switch to the Variables tab and review the list of Derived, Geometric, Solution, and User Defined

variables.

i. Right click the white space and click New to create a new variable named VelRatio .

ii. Click Ok to access the details view for VelRatio .

iii. Select Expression for the Method and set VelRatio to correspond to the Expression

VelocityRatio .

iv. Click Apply to create VelRatio .

Note

VelRatio is listed under the User-Defined type of Variables.

c. Contours, Isosurfaces, Vectors, Charts, etc. can now be plotted using this new variable.

24.8. Step 5: Comparison Study

1. Open a new ANSYS CFD-Post session

a. Go to File → Close CFD Post to close the existing ANSYS CFD-Post session.

b. In the ANSYS Workbench project schematic, right click the Solution cell of the parametric setup

component to transfer the solution data to a new Results component, as shown in Figure

24.40 (p. 379).

c. Rename the Results component to Comparison Study .



Figure 24.40 Creation of New Results Component and Updated Project Schematic

d. Double click the Results cell of Comparison Study to launch a new ANSYS CFD-Post session.

Note

As before, ANSYS CFD-Post automatically reads in the most recent solution set

(trial 004 ).

2. As shown in Figure 24.41 (p. 380), go to File → Load Results to load an additional solution set. Navigate

to the ~ice-cfdpost_files/dp0/IPK/Icepak/IcepakProj folder to pick trial001.cfd.datas the second solution set for the comparison study.



Step 5: Comparison Study

Figure 24.41 The Load Results Panel

3. Set up the display of the two solution sets.

a. Synchronize the camera and the visibility in the displayed views by turning on the corresponding

features from the Shortcuts Toolbar (located above the models in 3D viewer displays).

b. Rotate, Zoom, or Pan one of the displays and confirm that the other display follows suit.

c. Using the Shortcuts Toolbar, modify the display to a landscape view (switch from to )

4. As before, go to Insert → Location → Surface Group and create a Surface Group named Board-AndComponents .

Important

The Surface Group in this ANSYS CFD-Post session should include the board and

component surfaces from BOTH solution sets. Use the Location Selector to select all

but the last eight surfaces from each list. The easiest way to do this is to select all the

objects from both groups using Shift and the left mouse button, then deselecting the

cabinet objects from both groups using Ctrl and the left mouse button.



Figure 24.42 Display of BoardANDComponents

5. Deselect BoardAndComponents from User Locations and Plots.

6. As before, go to Insert → Contour and create a new contour object named TemperatureContoursand set its Locations to the BoardAndComponents Surface Group. Set Variable to Temperature

and click Apply.

7. Update the display of the Default Legend View (each display will need to be updated individually)

as before.



Step 5: Comparison Study

Figure 24.43 Display of Legend View

8. Go to Insert → Streamline and create a Streamline object named StreamlinesFans and edit

the Details as below:

a. Geometry tab: Select fan1_minx from both solution sets for Start From and set # of Points to

50 .

b. Color tab: Set Mode to Variable and select Temperature for Variable.

c. Symbol tab: Select Show Symbols and Show Streams. Set the Interval to 0.005 s.

d. Click Apply.



Figure 24.44 Display of Streamlines Comparison

e. Perform a detailed comparison study using the various features (Isosurface, Plane, Animation

etc.) discussed earlier in this tutorial.


In this tutorial, you learned how to import an ANSYS Icepak project from a .tzr file in ANSYS Workbench.

You then learned how to use a solution that was solved in ANSYS Icepak and postprocess it in ANSYS

CFD-Post. You also learned how to compare parametric solutions side-by-side in ANSYS CFD-Post.



Step 6: Summary

Chapter 25: High Density Datacenter Cooling

25.1. Introduction

This tutorial demonstrates how to model a datacenter using ANSYS Icepak.


• Use macros to create computer room air conditioning units (CRACs), server cabinets, power distribution

units (PDUs), and perforated floor tiles in the datacenter.

• Organize the model using groups.

• Include effects of gravity and turbulence in the simulation.

• Define object-specific meshing parameters.

• Create contours, particle traces, iso-surfaces to better understand the airflow patterns and temperature

stratification within the datacenter space.

25.2. Prerequisites


solved or read the tutorial "Finned Heat Sink" of this guide. Some steps will not be shown explicitly.


This tutorial considers a 1200 sq. ft. datacenter with a slab to slab height of 12 ft as shown in Figure

25.1 (p. 386). The datacenter consists of a 1.5 ft underfloor plenum and a 2 ft ceiling plenum. The CRACs

discharge cold air into the underfloor plenum. The cold air enters the main datacenter space mainly

through the perforated floor tiles and returns back to the air conditioning units as shown in Figure

25.2 (p. 386). The cooling load, as summarized in Table 25.1: Size and Capacity of Heat Sources in Datacen-

ter (p. 385) corresponds to the heat output from the server cabinets and the PDUs.

Table 25.1 Size and Capacity of Heat Sources in Datacenter

PowerSizeHeat Source

3000 W2 ft x 3 ft x 7 ftServer Cabinet

7000 W2 ft x 3 ft x 7 ftHigh Density

3600 W4 ft x 2 ft x 5 ftPDU



Figure 25.1 Geometry of the Datacenter Model

Figure 25.2 Expected Airflow Path




3. Specify a name for your project such as datacenter and click Create.





Note





25.5. Step 2: Set Preferences

1. Go to Edit → Preferences. The Preferences panel opens.

2. Go to Display in the Options node.

a. Select Float for the Color legend data format and enter 2 under Numerical display precision.

3. Go to Editing in the Options node.

a. Set the Default dimensions to Start/length.

4. Go to Object types in the Options node.

a. Turn off Decoration for all object types and update line Width to 2 for blocks, fans, openings,

plates, resistances and grilles.

Figure 25.3 The Preferences Panel - Object types



Step 2: Set Preferences

5. Go to Units in the Defaults node.

a. Click Set all to Imperial.

b. Click This project to apply the preferences to this project.


To build the model, you will first resize the cabinet to its proper size. Then you will create the features

of the datacenter, including CRACs (2), server cabinets (44), perforated floor tiles (44), raised floor (1),

dropped ceiling (1), return grilles (8), PDUs (2), cable trays (4), columns (2) and miscellaneous blockage

(1).

1. Resize the default cabinet.

a. Select the Cabinet in the Model tree and specify the following in the object geometry window:

b. Press Apply to resize the cabinet.

c. Click the Isometric view button ( ) to show a scaled-to-fit isometric view of the cabinet.

Note

The walls of the cabinet are adiabatic and do not participate in radiation by default.

Radiation will not be considered for this analysis.

2. Create the raised floor.

a. Click the Create plates button ( ).

ANSYS Icepak creates a free rectangular plate in the x-y plane in the center of the cabinet.

You need to change the orientation and size of the plate and its location within the cabinet.

b. In the object geometry window:

i. Set the Name to raisedfloor .

ii. Change the Plane to xz .

iii. Enter the following dimensions:

iv. Press Apply to resize and rename the object.

3. Create the first CRAC unit.

a. Go to Macros → Datacenter components → CRAC to open the CRAC panel.



b. Enter the dimensions as shown below in Figure 25.4 (p. 389).

c. Make sure the Flow direction is -Y .

d. Select Mass flow rate and input a value of 15.9 lbm/s.

e. Specify a Supply temperature of 55 F.

Figure 25.4 The CRAC Panel

Note

Mass flow rate has units of lbm/s.

f. Press Accept to create the CRAC unit.




Figure 25.5 The CRAC Unit in the Graphics Window

4. Set the per-object meshing parameters for the fans crac_intake and crac_exhaust .

a. Open the Mesh control panel by clicking the Generate mesh button ( ).

b. In the Local tab, check Object params and press Edit.

i. In the Per-object meshing parameters panel, Ctrl+left click crac_exhaust and

crac_intake to select both objects.

ii. Check the Use per object parameters option.

iii. Check the X count and Z count options and specify a Requested value of 4 for both options.



Figure 25.6 Per-object Meshing Parameters for the Fans

c. Click Done to close the Per-object meshing parameters panel.

d. Click Close to close the Mesh control panel.

5. Create a new group for the CRAC unit.

a. Select all the CRAC objects by Shift+left clicking cracunit and then crac_exhaust in the


b. Right click one of the selected objects and go to Create and then Group.

c. In the Create group panel, enter CRACs in the Name for new group text field.

d. Press Done to create the new group.

6. Create the second CRAC unit.

a. Expand the Groups node in the Model manager window.

b. Right click CRACs and select Copy.

c. In the Copy group panel, check Group name and enter CRACs.

d. Check Translate and set the Z offset to 10 ft.




Figure 25.7 The Copy Group CRACs Panel

e. Press Apply and Done to copy the CRAC unit and close the panel.



Figure 25.8 Two CRAC Units in the Graphics Window

f. Now may be a good time to Save the project ( ).

7. Create a row of server racks.

a. Go to Macros → Datacenter components → Rack (Front to Rear).

b. Input the dimensions as show below in Figure 25.9 (p. 394).

c. Set the Flow direction to -X .

d. Specify a Heat load of 3000 W.

e. Specify a Volume flow of 450 cfm.

f. Set the Number of racks to 11 .

g. Under Create additional racks along select +Z.




Figure 25.9 The Rack (Front to Rear) Panel

h. Press Accept to create the server racks.



Figure 25.10 Row of Server Racks in the Graphics Window




Note

The volumetric flow rate input for the recirculation opening is converted by ANSYS

Icepak to a mass flow rate input to the computational stage of the analysis. For

this conversion, ANSYS Icepak uses the density specified for Air in the materials

panel as shown below.

8. Create a new group for the server racks.

a. Select all the server rack objects by Shift + left clicking rack and then rack-opns.10 in the



c. In the Create group panel, enter RACKs in the Name for new group text field.


9. Create a second row of server racks

a. Right click RACKs in the Groups node and select Copy.

b. In the Copy group panel, check Group name and enter RACKs.

c. Check Rotate and Translate in the Operations group box.

d. Set the Axis to Y and the Angle to 180 .



e. Set the X offset to 7 ft.

Figure 25.11 The Copy Group RACKs Panel

f. Press Apply and Done to copy the row of server racks and close the panel.




Figure 25.12 Two Rows of Server Racks in the Graphics Window

10. Create a row of high density server racks.

a. Go to Macros → Datacenter components → Rack (Front to Rear).

b. Enter hdrack in the Name text field.

c. Input the dimensions as show below in Figure 25.13 (p. 399).

d. Set the Flow direction to -X .

e. Specify a Heat load of 7000 W.

f. Specify a Volume flow of 1000 cfm.

g. Set the Number of racks to 11 .

h. Under Create additional racks along select +Z.



Figure 25.13 The Rack (Front to Rear) Panel

i. Press Accept to create the high density server racks.

11. Create a new group for the high density server racks.

a. Select all the high density server rack objects by Shift+left clicking hdrack and then hdrack-opns.10 in the Model manager window.


c. In the Create group panel, enter HDRACKs in the Name for new group text field.


12. Create a second row of high density server racks.

a. Right click HDRACKs in the Groups node and select Copy.

b. In the Copy group panel, check Group name and enter HDRACKs.

c. Check Rotate and Translate in the Operations group box.

d. Set the Axis to Y and the Angle to 180 .

e. Set the X offset to 7 ft.

f. Press Apply and Done to copy the row of high density server racks and close the panel.




Figure 25.14 Two Rows of High Density Server Racks in the Graphics Window

13. Create a row of perforated tiles.

a. Go to Macros → Datacenter components → Tile.

b. Set the Number of tiles to 11 .

c. Enter the dimensions as show below in Figure 25.15 (p. 401).

d. Choose +Z.

e. Enter 0.35 for Uniform under % Open area.



Figure 25.15 Tile Panel

f. Press Accept to create the tiles.




Figure 25.16 Row of Tiles in the Graphics Window

14. Set the per-object meshing parameters for all the resistance objects.


b. In the Local tab, press Edit next to the Object params option.

i. In the Per-object meshing parameters panel, Shift+left click tile and then tile.10 to

select all the resistance objects.



iv. Check the Y count option and specify a Requested value of 3.



Figure 25.17 Per-object Meshing Parameters for the Tiles



15. Create a new group for the perforated tiles.

a. Select all the tile objects by Shift+left clicking tile and then tile_open_bottom.10 in the



c. In the Create group panel, enter TILEs in the Name for new group text field.


16. Create three more rows of perforated tiles.

a. Right click TILEs in the Groups node and select Copy.

b. In the Copy group panel, check Group name and enter TILEs .

c. Check Translate and set the X offset to 2 ft.

d. Press Apply and Done to copy the row of perforated tiles and close the panel.

e. Right click TILEs in the Groups node again and select Copy.

f. In the Copy group panel, check Group name and enter TILEs .

g. Check Translate and set the X offset to 14 ft.

h. Press Apply and Done to copy both rows of perforated tiles and close the panel.




Figure 25.18 Four Rows of Tiles in the Graphics Window

17. Create the ceiling plenum.

a. Click the Create plates button ( ).


i. Set the Name to ceilingplenum .

ii. Change the Plane to xz .



18. Create a return grille.

a. Click the Create grille button ( ).

b. Double click the grille.1 object in the Model manager window to open the Grille panel.

c. In the Info tab, enter ceiling-return under Name and enter CEILING-RETURN under

Groups.

d. In the Geometry tab, set the Plane to X-Z and enter the following dimensions:



e. In the Properties tab, set the Free area ratio to 0.5 .

f. Press Done to apply the settings and close the panel.

19. Create two rows of return grilles.

a. Right click CEILING-RETURN in the Groups node and select Copy.

b. Set the Number of copies to 2.

c. In the Copy group panel, check Group name and enter CEILING-RETURN.

d. Check Translate and set the Z offset to 9 ft.

e. Press Apply and Done to copy the return grille and close the panel.

f. Right click CEILING-RETURN in the Groups node again and select Copy.

g. In the Copy group panel, check Group name and enter CEILING-RETURN.

h. Check Translate and set the X offset to -14 ft.

i. Press Apply and Done to copy the row of return grilles and close the panel.

Figure 25.19 Two Rows of Return Grilles in the Graphics Window




20. Create two more return grilles.

a. Click the Create grille button ( ).

b. Double click the newly created object to open the Grille panel.

c. In the Info tab, enter ceiling-return-crac1 under Name and select CEILING-RETURNfrom the Groups drop-down list.

d. In the Geometry tab, set the Plane to X-Z and enter the following dimensions:

e. In the Properties tab, set the Free area ratio to 0.5 .

f. Press Done to apply the settings and close the panel.

g. Right click the vent ceiling-return-crac1 from the Model tree and select Copy.

h. In the Copy group panel, check Group name and enter CEILING-RETURN.

i. Check Translate and set the Z offset to 10 ft.

j. Press Apply and Done to copy the return grille and close the panel.

k. Right click ceiling-return-crac1.1 and Rename the object to ceiling-return-crac2 .



Figure 25.20 Two CRAC Return Grilles in the Graphics Window

21. Set the per-object meshing parameters for the return grilles.


b. In the Local tab, press Edit next to the Object params option.

i. In the Per-object meshing parameters panel, Shift+left click ceiling-return and then

ceiling-return.3 to select all the return grilles.






Figure 25.21 Per-object Meshing Parameters for the Return Grilles



22. Create a PDU.

a. Go to Macros → Datacenter components → PDU to open the PDU panel.

b. Enter the dimensions as shown below in Figure 25.22 (p. 409).

c. Set the PDU flow direction to +Y.

d. Set the Heat output to 3600 W.

e. Set the Percent open area on top and the Percent open area on bottom to 0.25 .



Figure 25.22 The PDU Panel

f. Press Accept to create the PDU.

23. Set the per-object meshing parameters for the grilles pdu_vent_in and pdu_vent_out .


b. In the Local tab, check Object params and press Edit.

i. In the Per-object meshing parameters panel, Ctrl+left click pdu_vent_in and

pdu_vent_out to select both objects.





24. Create a new group for the PDU.

a. Select all the PDU objects by Shift+left clicking pdu_unit and then pdu_part4 in the Model

manager window.


c. In the Create group panel, enter PDUs in the Name for new group text field.


25. Create the second PDU.




a. Right click PDUs in the Groups node and select Copy.

b. In the Copy group panel, check Group name and enter PDUs.

c. Check Translate and set the X offset to 14 ft and the Z offset to 28 ft.

d. Press Apply and Done to copy the PDU and close the panel.

Figure 25.23 Two PDUs in the Graphics Window

e. Now may be another good time to Save the project ( ).

26. Create blockages.

a. Click the Create blocks button ( ).


i. Set the Name to piping and the Group to BLOCKAGE.

ii. Set the Type to Hollow.





c. Click the Create blocks button ( ).

d. In the object geometry window:

i. Set the Name to blockage and the Group to BLOCKAGE.




27. Create columns.



i. Set the Name to column1 and the Group to COLUMNS.




c. Click the Create blocks button ( ).

d. In the object geometry window:

i. Set the Name to column2 and the Group to COLUMNS.




28. Create cabletrays.



i. Set the Name to cabletray1 and the Group to CABLETRAYS.







c. Create three more cabletrays.

i. Right click CABLETRAYS in the Groups node and select Copy.

ii. In the Copy group panel, check Group name and enter CABLETRAYS.

iii. Check Translate and set the X offset to 6 ft.

iv. Press Apply and Done to copy the cabletray and close the panel.

v. Right click CABLETRAYS in the Groups node again and select Copy.

vi. In the Copy group panel, check Group name and enter CABLETRAYS.

vii. Check Translate and set the X offset to 14 ft.

viii. Press Apply and Done to copy the cabletrays and close the panel.

Figure 25.24 The Completed Model




1. Click the Generate mesh button ( ).

2. In the Mesh control panel, enter 2 ft, 0.5 ft, and 1 ft for the Max element size for x, y, and z, respect-

ively. Change the Minimum gap values to 1 in, 0.36 in, and 1 in for x, y and z, respectively.

Figure 25.25 Mesh Control Panel

Note

The units for the Minimum gap values are in inches.

3. Click Generate.

4. Use the Display and Quality tabs to view the mesh and check the mesh quality.

5. Click Close to close the panel once you have finished viewing the mesh.

25.8. Step 5: Create Monitor Points

Create two temperature monitor points for the CRAC fans exhaust fans by dragging crac_exhaustand crac_exhaust.1 from the Model node to the Points node. ANSYS Icepak will automatically

monitor values at the centers of these objects. The default setting is to monitor Temperature. You can

also monitor Pressure and/or Velocity by double clicking the monitor point in the Points folder and

choosing which variables to monitor at that location.



Step 5: Create Monitor Points

Figure 25.26 Creating Monitor Points



a. In the General setup tab:

i. Turn Off the Radiation.

ii. Select Turbulent and Zero equation for the Flow regime.

iii. Enable the Gravity vector.

b. In the Defaults tab:

i. Select Mica-Typical from the Insulators section of the Default solid drop-down list.

ii. Select Paint-non-metallic from the Paint section of the Default surface drop-down list.

c. In the Transient setup tab:

i. Set the initial Y velocity to be 0.5 ft/s (a non-zero initial velocity is recommended for

problems involving natural convection).

d. In the Advanced tab:

i. Select the Ideal gas law (recommended for problems involving significant temperature dif-

ferences).

ii. Check Operating density and keep the default value.

e. Press Accept to apply the settings and close the panel.


a. Change the Number of iterations to 1000 and the Convergence criteria for Energy to 1e-6 .

b. Click Accept to apply the settings and close the panel.


a. Set the Discretization scheme for Pressure as Body Force Weighted.

b. Set the Under-relaxation to 0.2 for Momentum and to 0.1 for Body forces.

c. Click Accept to apply the settings and close the panel.











1. Go to Solve → Run solution.

2. In the Results tab, check Write CFD Post data.


ANSYS Icepak begins to calculate a solution for the model, and a separate window opens where



calculation.

Upon completion of the calculation, your residual and monitor plots will look something like Figure

25.27 (p. 416) and Figure 25.28 (p. 417). You can zoom in the residual plot by using the left mouse.

Note


plots may not look exactly the same as Figure 25.27 (p. 416) and Figure 25.28 (p. 417).




Figure 25.27 Solution Residuals



Figure 25.28 Temperature Point Monitors

4. Click Done in the Solution residuals and Temperature Point monitors windows to close them.


The objective of this exercise is to consider the airflow patterns and identify problem areas such as hot

spots, stagnant zones, and recirculation zones through out the datacenter. You will accomplish this by

examining the solution using ANSYS Icepak's graphical postprocessing tools.

1. Display contours of temperature on the CRACs, Racks, and PDUs.

a. Click the Object face button ( ).

b. Enter surface-temp-contours in the Name field.

c. In the Object drop-down list, expand the Groups node and Ctrl+left click CRACs, HDRACKs,PDUs, and RACKs, and click Accept.




d. Check Show contours and click Create.

e. Click Done to close the panel.

Figure 25.29 Object Face Temperature Contours

2. Display animated contours of temperature on plane cuts in all 3 coordinate planes.

a. Right click surface-temp-contours under the Post-processing node in the Model manager

window, and make the object face inactive by unchecking Active in the context menu.

b. Click the Plane cut button ( ).

c. Enter plane-temp-contours in the Name field.



d. Check Show contours and click Create to view a plane cut of the temperature contours.

Figure 25.30 Plane Cut Temperature Contours

e. Check the Loop mode option and click Animate to display a loop of the plane cut traversing

from the min z to the max z side of the datacenter.

f. Click Interrupt on the progress bar to return to the Plane cut panel.

g. Repeat the above procedure for plane cuts in the Y-Z and X-Z planes by changing the Set pos-

ition to X plane through center and Y plane through center respectively.

h. Click Done to close the panel.

3. Display animated contours of temperature on an isosurface.

a. Right click plane-temp-contours in the Model manager window and make the plane cut

inactive by unchecking Active in the context menu.

b. Click the Isosurface button ( ).

c. Enter iso-temp in the Name field.

d. Enter 90 in the Value field.

e. Check Show contours and click Create to view the isosurface of 90°F.




Figure 25.31 Isosurface of 90°F

f. To view an a loop of isosurfaces from 90°F to 80°F:

i. In the Animation group box, enter 90 for Start, 80 for End, and 10 for Steps.

ii. Check the Loop mode option and click Animate.

iii. Click Interrupt on the progress bar to return to the Isosurface panel.

g. Click Done to close the panel.

4. Display airflow patterns in the datacenter.

a. Right click iso-temp in the Model manager window and make the isosurface inactive by un-

checking Active in the context menu.

b. Click the Object face button ( ).

c. Enter airflow in the Name field.

d. In the Object drop-down list, expand the Groups node and Ctrl+left click CEILING-RETURN,

HDRACKs, PDUs, RACKs, and TILEs , and click Accept.



e. Check Show particle traces and click Parameters.

f. Set the Display options to Mesh points.

g. Set the End time under Particle options to 5.

h. Check Loop mode under Animation and set the Steps to 50 .

i. Click Apply to display the airflow patterns.

Note

ANSYS Icepak will take a few moments to generate the airflow patterns.




Figure 25.32 Particle Traces

j. Click Animate to visualize the airflow patterns in a transient manner.

k. View the animated airflow patterns from various angles from the Orient menu.

l. Press Interrupt to stop the animation.

m. Click Done in the Object face particles and Object face panels to close them.

n. Right click airflow in the Model manager window and make the particle traces inactive by

unchecking Active in the context menu.

5. Report the volumetric flow rate distribution at the perforated floor tiles.

a. Go to Report → Summary report to open the Define summary report panel.

b. Click New to get a new field to define the Summary report.

c. In the Objects drop-down list, expand the Groups node and select TILEs , and click Accept.

d. Select Volume flow from the Value drop-down list and deselect Comb.



e. Click Write to display the summary report.

f. Click Done to close the Report summary data panel.

g. Click Close to close the Define summary report panel.

6. Save ( ) the project and Close ANSYS Icepak.




25.13. Step 10: Additional Exercise: Visualize and analyze the results in

ANSYS CFD-Post

In addition to using the postprocessing tools contained within ANSYS Icepak, you can also postprocess

using the advanced tools in ANSYS CFD-Post through ANSYS Workbench. See "Postprocessing Using

ANSYS CFD-Post" for details on how to use the features in ANSYS CFD-Post.


In this tutorial, you learned how to model a datacenter using macros, and how to organize a model

using groups. You also learned how to use animated postprocessing objects to examine the results.



Chapter 26: Design Modeler - Electronics

26.1. Introduction

This tutorial demonstrates how to use ANSYS DesignModeler to convert a model for analysis in ANSYS

Icepak.


• Use the Slice, Opening, Fan, and Simplify options in ANSYS DesignModeler.

• Organize the model using Parts.

26.2. Prerequisites

• Familiarity with the ANSYS Workbench interface

• Familiarity with the ANSYS Icepak interface


You will convert an imported STEP file for use in ANSYS Icepak. Figure 26.1 (p. 425) shows the geometry

in ANSYS DesignModeler before the conversion and in ANSYS Icepak after conversion.

Figure 26.1 Comparison of the Geometry in ANSYS DesignModeler and ANSYS Icepak


1. Open ANSYS DesignModeler through ANSYS Workbench.

a. Start a new ANSYS Workbench session.



b. Drag a Geometry (ANSYS DesignModeler) component module from the Toolbox and drop it on

the Project Schematic window as shown in Figure 26.2 (p. 426).

c. Rename the Geometry component module to STEP Import and DME to IcepakTranslation . To rename the title, double click on the title Geometry or click the left mouse

button on the down arrow ( ) and select the Rename option from the drop down list.

Figure 26.2 Creating a Geometry Component Module

d. Save the project (name the project as DME).

e. Double click cell A2 to open ANSYS DesignModeler.


1. Once ANSYS DesignModeler opens, select Millimeter as the desired unit, and press OK.



2. Go to File → Import External Geometry File and select DME.stp and press Open.

3. Click to create the model.

Figure 26.3 Imported Model

26.6. Step 3: Add Shortcuts to the Toolbar

1. Go to Tools → Options

2. In the Options panel, go to DesignModeler → Toolbar.

3. Set Slice, Freeze, and Electronics to Yes .



Step 3: Add Shortcuts to the Toolbar

Figure 26.4 Options Panel

4. Press OK to add the options to the toolbar.

Note

• The Electronics drop down menu in the toolbar contains several options:

• You can also access the option from the Create menu.

• You can also access the and Electronics options from the Tools menu.

26.7. Step 4: Edit the Model for ANSYS Icepak

1. Click to make the model transparent and to allow for the Slice operation.

2. Check which bodies are already recognized as ANSYS Icepak objects.

a. Go to Electronics → Show Ice Bodies. Only bodies with simple geometries recognized as ANSYS

Icepak objects will be visible.



Figure 26.5 Bodies Recognized as ANSYS Icepak Objects

Note

We will not have to make modifications to export these bodies into ANSYS Icepak.

b. Go to Electronics → Show CAD Bodies. Only bodies with complex geometries not recognized

as ANSYS Icepak will be visible.



Step 4: Edit the Model for ANSYS Icepak

Figure 26.6 Bodies not Recognized as ANSYS Icepak Objects

Note

These are the bodies we will have to modify in order to export these bodies into

ANSYS Icepak.

c. Go to Electronics → Revert View to return to the previous display.

3. Create a Slice for one set of fins.

a. In the Tree Outline, right click Housing and select Hide All Other Bodies.

b. Select from the Shortcuts toolbar.

c. In the Details view, set the Slice name to FinsSlice1 .

d. Select Slice by Surface for Slice Type.

e. Click on the field to the right of Target Face and select the one of faces at the base of the fins,

as shown in Figure 26.7 (p. 431) and click Apply.



Figure 26.7 FinsSlice1 Face Selection

Note

If you cannot select the face, try pressing the Model Faces selection filter ( ).

f. Make sure Slice Targets is set to Selected Bodies .

g. Click the field to the right of Bodies and select the Housing body.

h. Click Apply and then .

4. Likewise, create a Slice for the other set of fins.

a. Use the procedure described above on the other set of fins and name the second Slice FinsS-lice2 .




Note

Make sure that the Bodies selection is the larger section of the housing containing

the fins.

Figure 26.8 FinsSlice2 Bodies Selection

5. Create Parts for the sliced fins.

Note

The Parts will become Assemblies in ANSYS Icepak.

a. Press +Y on the Triad (the axes) to get a clear view of the fins.

b. Select Box Select from the Shortcuts toolbar.

c. Select the Bodies selection filter ( ).

d. Drag the bounding box around one set of fins, and rotate the model to make sure that all the

fins are selected as shown in Figure 26.9 (p. 433) (you should have 13 bodies selected).



Figure 26.9 Selecting a Row of Fins

e. Right click anywhere in the Model View and select Form New Part.

f. In the Details view, set the Part name to Fins1 and press enter on the keyboard.

g. Repeat steps a to f for the other set of fins, except name the part Fins2 .

6. Create a Housing slice.

a. Select from the Shortcuts toolbar.

b. In the Details view, set the Slice name to HousingSlice1 .

c. Select Single Select from the Shortcuts toolbar.




d. Click the field to the right of Target Face and select the inner face of bottom of the Housing as

shown in Figure 26.10 (p. 434) and press Apply.

Figure 26.10 HousingSlice1 Selection

e. Make sure Slice Targets is set to Selected Bodies .

f. Click the field to the right of Bodies and select the Housing object in between the fins.



Figure 26.11 HousingSlice1 Bodies Selection

g. Click Apply and then .

7. Create another Housing slice.

a. Select from the Shortcuts toolbar.

b. In the Details view, set the Slice name to HousingSlice2 .

c. Select the inner face of the top of the Housing as shown in Figure 26.12 (p. 436) and press Apply.




Figure 26.12 HousingSlice2 Face Selection

d. Click the field to the right of Bodies and select the top part of the Housing object in between

the fins.

e. Click Apply and then .

f. You should have ten Housing objects outside of the Fins parts in the Tree Outline.

8. Create Openings for the fan.

a. Show all bodies again by right clicking one of the objects in the Tree Outline and clicking Show

All Bodies

b. Go to the +Y view.

c. Go to Electronics → Opening.

d. In the Details view, set the Opening name to FanOpenings .

e. Click the field to the right of Faces and select the face as shown in Figure 26.13 (p. 437) and press

Apply and .



Figure 26.13 FanOpenings Face Selection

9. Create Openings for the back panel.

a. Go to the -Y view.

b. Go to Electronics → Opening.

c. In the Details view, set the Opening name to BackOpenings .

d. Click the field to the right of Faces and select the face as shown in Figure 26.14 (p. 437) and press

Apply and .

Figure 26.14 BackOpenings Face Selection

10. Create a Fan.

a. Right click the Fan body in the Tree Outline and select Hide All Other Bodies.




Note

If you cannot view the object correctly, press Zoom to Fit ( ).

b. Go to Electronics → Fan.

c. In the Details view, set the Fan name to FanGeom.

d. Click the field to the right of Body To Extract Fan Data, select the entire fan body and press

Apply.

e. Click the field to the right of Hub/Casing Faces and select the faces as shown in Figure 26.15 (p. 438).

Figure 26.15 Hub/Casing Faces Selection

Note

You can select multiple faces by holding down Ctrl and left clicking the objects.

f. Click Apply and .

Note

Although it may seem like there was no change, this step creates a fan object in

ANSYS Icepak. To confirm this, you can go to Electronics → Show Ice Bodies

and check if the fan is present.



g. Add the fan to the Front-Panel part.

i. In the Tree Outline, select the Front-Panel part and then Ctrl and left click the Fan object.

ii. Right click the Fan object and select Form New Part.

iii. In the Details view, rename the Front-Panel Part to Front-Panel-Fan .

11. Perform a Simplify operation on the Housing.

a. Show all bodies again by right clicking one of the objects in the Tree Outline and clicking Show

All Bodies

b. Go to Electronics → Simplify.

c. In the Details view, set the Simplify name to HousingFrontBack .

d. In the field to the right of Simplification Type, select Level 1 .

e. Click the field to the right of Select Bodies and select the front and the rear panels of the Housing

as shown in Figure 26.16 (p. 439).

Figure 26.16 HousingFrontBack Bodies Selection

f. Click Apply and .

12. Perform a Simplify operation on the PWB and the T0220 objects.

a. Select all the Housing, Fin, Panel, Opening, and Fan objects from the bottom of the Tree Outline

by holding down Shift and using the left mouse button.

b. Right click one of the selected objects and select Hide Body to view just the internal components.

c. Go to Electronics → Simplify.

d. In the Details view, set the Simplify name to PWB_T0220.

e. In the field to the right of Simplification Type, select Level 1 .




f. Click the field to the right of Select Bodies and select the PWB and all the HS_AF0 and

T0220_Case objects.

Note

Because they are simple bodies that are already recognized as ANSYS Icepak objects,

do not select the LEAD_1_AF0 or the HS_AF0 objects.

i. Go to the +Z view.

ii. Make sure the Select Mode is Single Select.

iii. Hold down Ctrl and select the objects as shown in Figure 26.17 (p. 440).

Figure 26.17 PWB_T0220 Bodies Selection

iv. Using this method, only the 13 correct bodies will be selected.

g. Click Apply and .

13. Add all the package objects to the Parts.

a. Change the Selection Mode to Box Select and make sure the selection filter is set to Bodies.



b. Select a package object as shown in Figure 26.18 (p. 441). There should be 6 bodies selected.

Figure 26.18 Package Object Selection

c. Right click the model and select Form New Part. All the bodies will be added to the part.

d. Name the part T0220_Case1 .

e. Repeat steps a to e for the rest of the packages, except naming the parts T0220_Case2 ,

T0220_Case3 , etc.

14. Perform a Simplify on the Coil.

a. Go to Electronics → Simplify.

b. In the Details view, set the Simplify name to CoilAssembly .

c. In the field to the right of Simplification Type, select Level 1 .

d. Click the field to the right of Select Bodies and select the bodies as shown in Figure 26.19 (p. 442).

There should be 4 bodies selected.




Figure 26.19 Coil Bodies Selection

e. Click Apply and .

15. Add the rest of the Coil bodies to the part.

a. Make sure the selection filter is set to Bodies.

b. Make the same selection as in the simplify operation. Notice that there are now 8 bodies instead

of 4.

c. Right click the model and select Form New Part.

d. In the Details view, set the Part name to CoilAssembly2 .

16. Perform a Simplify on the Capacitors.

a. Go to Electronics → Simplify.

b. In the Details view, set the Simplify name to Capacitors .

c. In the field to the right of Simplification Type, select Level 3 .

d. Click the field to the right of Select Bodies and select the bodies as shown in Figure 26.20 (p. 443).

There should be 3 bodies.



Figure 26.20 Capacitors Bodies Selection

e. Click Apply.

f. Set the Face Quality to Medium

g. Click .

17. Form a part for the Capacitors.


b. Make the same selection as the simplify operation. There should still be 3 selected bodies.

c. Right click the model and select Form New Part.

d. In the Details view, set the Part name to Capacitors .

18. Form parts for the Heat Sink and Components.


b. Follow the same steps as before to create a part called BGAHS for the Heat Sink and Componentsfor the Components:




Figure 26.21 BGAHS and Components Parts Selections

19. Right click a body in the Tree Outline and select Show All Bodies. Your model should look like Figure

26.22 (p. 444) and your Tree Outline should look like Figure 26.23 (p. 445).

Figure 26.22 Final Model in ANSYS DesignModeler



Figure 26.23 Final Tree Outline

Note

Some of your parts and bodies may be in a different order than what is shown in Figure

26.23 (p. 445).

20. Check if all the bodies have been converted to ANSYS Icepak objects.

a. Go to Electronics → Show CAD Bodies.

b. Confirm that the view contains no bodies. This means all the bodies have been recognized by

ANSYS Icepak.

21. The model is now ready to use in ANSYS Icepak.

26.8. Step 5: Opening the Model in ANSYS Icepak

1. Go to File → Save Project and then File → Close DesignModeler.

2. In ANSYS Workbench, drag an ANSYS Icepak component to cell A2 to create an ANSYS Icepak component

module.



Step 5: Opening the Model in ANSYS Icepak

Figure 26.24 Creating an ANSYS Icepak Component Module

3. Double click the Setup cell (B2) to open the model in ANSYS Icepak.

4. In the model manager window, right click the Model node and select Expand all to view the geometry

inside the assemblies.

5. Notice that the bodies have been successfully transferred into ANSYS Icepak.



Figure 26.25 Final Model


In this tutorial, you learned how to get a CAD model ready for ANSYS Icepak using ANSYS DesignModeler.

You used the slice, simplify, openings, and fan operations to convert the model.



Step 6: Summary

Index

BBGA-package, 157, 321

CCAD

geometry, 245

import, 247

CFD Post, 351

CFD Post in Workbench, 351

cold-plate, 97, 101

DDatacenter cooling

high density, 385

Design Modeler

electronics, 425

Dimensions tab, 322

EEdit object panel, 7

Electronics

Design Modeler, 425

Ffinned heat sink, 3, 17

Functions

compound, 178

objective, 178

primary, 178

Hheat pipe, 107, 113

heat sink, 49

finned, 3, 17

inline or staggered, 157

heat transfer coefficient, 325

help

obtaining support, 2

hex-dominant, 257

IIcepak in Workbench, 339

import

CAD file, 247

IDF, 235, 268

tcb file, 322

trace layer, 271, 333

individual side specification, 79

Jjoule heating, 283

Lloss coefficient, 143

loss coefficient vs Re, 155

Mmesh exercise, 133

microelectronics, 295

modeling

model layers separately, 281

radiation, 196

monitor point, 308

mouse conventions, 2

multi-level meshing, 311, 314

Nnon-conformal

assembly, 101

mesh, 121, 127, 129

nested, 113

Oobject parameters, 221

obtaining support, 2

optimization run, 181

orthotropic material properties, 110

Pparam value, 175

parameterization, 71

parametric runs, 162

parametric trials, 147

multiple trials, 84

Rradiation model

discrete ordinates, 185, 197

ray tracing, 197

rf amplifier, 37, 53

Ssearch fan library, 50

summary report, 126

support

obtaining help, 2



TThermal Resistance, 173

trace heating, 283

trace layer, 267

import, 271, 333

transient simulation, 201

typographical conventions, 1

WWorkbench

Icepak, 339

Zzero slack, 136, 331, 336

zoom-in modeling, 217, 224


Index

ansys icepak tutorials

Documents