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Module 01: Core Skills Introduction to ANSYS Meshing

17.0 Release

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In this lecture we will learn: • Meshing Fundamentals • ANSYS Meshing interface • Geometry concepts • Meshing methods • Diagnostics & Usability • Display Option • Mesh Statistics & Mesh Metrics

Overview

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Structural Mechanics: From Linear Statics

Fluid Mechanics: From Single-Phase Flows

Electromagnetics: From Low-Frequency Windings

Systems: From Data Sharing

To High-Speed Impact

To Multiphase Combustion

To High-Frequency Field Analysis

To Multi-Domain System Analysis

Breadth of Technologies

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Preprocessing Workflow

Geometry Import / Creation

Geometry Cleanup / Modifications

Meshing Preprocessing and Solution

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Core Skills

Global Controls

Local Controls

Mesh Quality

Meshing Methods

Mesh Process & Course Plan

Module 1 Module 2

Module 3

Module 4

Module 5

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ANSYS Meshing is a component of ANSYS Workbench • Meshing platform • Combines and builds on strengths of preprocessing offerings from ANSYS:

– ICEM CFD, TGRID (Fluent Meshing), CFX-Mesh, Gambit

Able to adapt and create Meshes for different Physics and Solvers • CFD: Fluent, CFX and POLYFLOW • Mechanical: Explicit dynamics, Implicit • Electromagnetic

Integrates directly with other WB systems

What is ANSYS Meshing

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Purpose of the Mesh • Equations are solved at cell/nodal locations

– Domain is required to be divided into discrete cells (meshed)

Mesh Requirements • Efficiency & Accuracy

– Refine (smaller cells) for high solution gradients and fine geometric detail. – Coarse mesh (larger cells) elsewhere.

• Quality – Solution accuracy & stability deteriorates as mesh cells deviate from ideal

shape

Meshing Fundamentals

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Fluid Flow (Fluent), Static Structural,…

ANSYS Meshing is launched within Workbench – 2 ways:

From Analysis Systems

Mesh

From Component Systems

Double click Mesh in the

System

or right click and select Edit

Launching ANSYS Meshing

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Mesh Metrics

Graphics window

Section Planes

Manage views

Details view

Outline

Toolbars

Units Bar Entity Details Bar

Message window

Worksheet

Graphical User Interface

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Three default sections • Geometry

– Bodies

• Coordinate Systems – Default global & user defined systems

• Mesh – Meshing operations (controls & methods) displayed in the order in which they are inserted

In the tree • Right clicking on any object

– launches a context sensitive menu – Example: contains commands to generate, preview, clear mesh etc.

Outline

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Accessing Object Details • Select an object (in the Outline)

– Related information to that object are displayed in the Details View below – Ex: Select a body (“Fluid”) in the Outline

• Details of “Fluid” : contains graphical and geometric details – To access meshing details

• Click the Mesh object or any of the inserted objects

• The Details View provides options to – review, – edit, or – input

values for every object in the Tree

Details View

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• Geometry composed of Multiple parts – No connection between parts (no face sharing)

‘Contact Region’ is automatically created between 2 faces

Each part meshed independently

Results in Non-conformal interface. Meshes do not match. No nodes connection.

Independent faces

Grid interface - Fluent

GGI - CFX

Geometry Configuration – Multiple Parts

Contact - Mechanical

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• Geometry composed of multiple bodies in a part – Depend on ‘Shared Topology method’ (in DM)

• None – Results in a no connection between the bodies (similar to

multiple parts) • Automatic

Common face acts as ‘Interior’

Note: The CFX users will still get duplicate nodes at interface in CFX, which is fine for its solver

Geometry Configuration – Multi-body Parts

Faces in contact imprinted & fused to form a single face shared between 2 bodies

Results in Conformal mesh

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• Geometry composed of multiple bodies in a part • Imprints

Faces are imprinted on each other ‘like’ faces

Contact Region is automatically created

non conformal interface

For identical mesh on these faces, use ‘Match Control’ Results in unconnected mesh

Grid interface - Fluent

GGI - CFX

Geometry Configuration – Multiple – body Parts

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• 3D cell Types • First Meshing Approach

Part/Body based • Meshing occurs at part or

body level. • Meshing Methods are scoped

to individual bodies. • Method assignment can be

automatic or manual. • Bodies contained in one part

are conformally meshed.

Part/Body Methods • Tetrahedrons.

− Tetras only • Sweep.

− Prisms & hexahedrons • MultiZone.

− Mainly hexahedron • Hex Dominant

− Not for CFD • Automatic.

− Sweep + PC Tet (Depends on bodies) or PC Tet

Meshing – 3D Geometry

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Turning wireframe mode on

Default mesh display

Turning on Mesh display by body connection.

Diagnostics: Mesh display By Body Connection (New in R17.0)

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● Close Vertices: Checks for vertices that are very close together: – Scale can be adjusted depending on model sizes

Diagnostics: Close vertices (New in R17.0)

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Named Selections are groups of geometric or finite element entities:

• Named selections can be created either by selecting the desired items and clicking the “Named Selection” icon in the context toolbar or RMB > Named Selection OR using the named selection worksheet (shown later).

• Named selections must be composed of “like” entities (all surfaces or all edges, all nodes, etc.).

RMB

Named Selections (1)

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A new criteria selection can be based on an initial selection: • Make an initial selection followed by a RMB > “Create Named Selection”. • Note, initial selection must be a single entity.

RMB >

Selection here will create the first row of the worksheet.

Convert to nodal named selection immediately.

Named Selections (2)

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In many detail window fields Named Selections can be referenced directly: − In the Details view, change “Scoping Method” from “Geometry Selection” to “Named

Selection” − Select the “Named Selection” from the pull-down menu

− A named selection toolbar provides quick access to basic controls “View > Toolbars > Named Selections”:

Named Selections (3)

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Worksheet Summary:

• As can be seen, numerous controls are available in the worksheet. See the documentation for a complete discussion of each.

• As discussed elsewhere in this course the “Convert To” action is used to change a geometry named selection (face, edge, etc.) to a nodal named selection.

When creating named selections using worksheet criteria a set of tolerances is available if needed:

• Tolerance adjustment is usually only necessary in special circumstances like models in micro units or node selections in dense meshes.

Named Selections (4)

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● Body Criterion Based Selection by keywords (Name) ● Body Criterion Based Selection by Thickness (for sheets)

● Convert to options based on connectivity

– Find attached faces to edges based on any edge/all edges – Find attached edges to vertices based on any vertex/all vertices

Named Selections (5)

New in R17.0

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Usability: Option to save mesh out to separate file (New in R17.0)

● When “Save Mesh Data in Separate File” is on the mesh is saved as a separate file (*.acmo).

● Duplication, Resume, Replace, and Save will handle the separate database and acmo files.

● Clear generated data will not remove the acmo file. Reset will remove the acmo file.

● Design Points (also w/RSM) support the separate database and acmo files.

This functionality is particularly helpful on Linux

to keep file sizes smaller.

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Usability: Better Meshing Status in R17.0 ● Progress is reported as parts are meshed in parallel ● As a part is meshed the topology (edges, faces, bodies) are highlighted to show what is

being worked on – This can be turned off by unchecking “Highlight” – If user stops meshing, entity will stay highlighted, allowing user to find problematic geometry easier

If user stops meshing, parts that have been meshed are done. Restarting meshing resumes only with unmeshed parts

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● Mesh controls can now be grouped for easier organization

● Option: Group All Similar Children, will group all objects based on type

● Options to suppress, rename, nest groups, ungroup, delete objects in group

● Drag and drop capabilities to modify the grouping

Usability: Folders for Meshing Controls in R17.0

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• Displays mesh color by quality metrics • Options to probe quality or show min/max • Contour band can be adjusted

Display mesh contours

Find Min or Max value

Probe Element Values

Display Option: Color by quality

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Displays internal elements of the mesh • Elements on either side of plane can be displayed • Toggle between cut or whole elements display • Elements on the plane

Edit Section Plane button can be used to drag section plane to new location • Clicking on “Edit Section Plane” button will make section plane’s anchor to appear

Multiple section planes are allowed

For large meshes, it is advisable to switch to geometry mode (click on geometry in the Tree Outline), create the section plane and then go back to mesh model

Section Planes (1)

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Section Planes (2)

● Shaded section planes (New in R17.0) – Shaded or hollow section plane

– Plot by body color or same color for section plane

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• Displays mesh information for Nodes and Elements

• List of quality criteria for the Mesh Metric – Different physics and different solvers have different requirements for mesh quality

Mesh metrics available in Workbench Meshing include:

– Element Quality – Aspect Ratio – Jacobean Ration – Warping Factor – Parallel Deviation – Maximum Corner Angle – Skewness – Orthogonal Quality

For Multi-Body Parts, go to corresponding body in Tree Outline to get its separate mesh statistics per part/body

Mesh Statistics & Mesh Metrics

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• Displays Mesh Metrics graph for the element quality distribution

• Different element types are plotted with different color bars

• Can be accessed through menu bar using Metric Graph button

• Axis range can be adjusted using controls button (details next slide)

• Click on bars to view corresponding elements in the graphics window – Use to help locate poor quality elements

Mesh Metric Graph

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• Elements on Y-Axis can be plotted with two methods; – Number of Elements – Percentage of Volume/Area

• Options to change the range on either axis • Specify which element types to include in graph

– Tet4 = 4 Node Linear Tetrahedron – Hex8 = 8 Node Linear Hexahedron – Wed6 = 6 Node Linear Wedge (Prism) – Pyr5 = 5 Node Linear Pyramid – Quad4 = 4 Node Linear Quadrilateral – Tri3 = 3 Node Linear Triangle

• Te10, Hex20, Wed15, Pyr13, Quad8 & Tri6 non-linear elements

Mesh Metric Graph Controls

For more information about the different mesh metrics please consult module 05: Mesh Quality

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What have we learnt in this session: • The global process to run ANSYS Meshing • On overview of the interface and • The various Geometry configurations

– Multiple parts – Multi-body parts – Multiple body parts

• Meshing methods – Part/body based

• Section Planes • Diagnostics & Usability • Mesh Statistics & Mesh Metrics • Display option

And the associated shared topology option

Summary

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Workshop 1.1 FEA – ANSYS WB Meshing Basics