r12 meshing feature presentation

© 2008 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

Workbench MeshingANSYS 12.0Workbench MeshingANSYS 12.0

Erling EklundBen KlinkhammerErling EklundBen Klinkhammer


Workbench MeshingIntroductionWorkbench MeshingIntroduction


Workbench Meshing Overview

• Workbench process automation:– Physics-aware meshing

– Meshing in batch – Parametric/Persistent meshing

• Adding controls for meshing flexibility:– mesh type/method– mesh sizing

– mesh alignment– mesh quality

– mesh feature capturing


Workbench process automation

• Meshing comes as a cell of a Workbench Analysis System (Mesh/Model)

• Or as it’s own Component System.

• Regardless of what System the Mesh/Model cell is invoked from the meshing tools are the same

• However, the meshing defaults are based on the physics preference of the system

• The mesh is provided to any downstream system– Downstream systems can be linked to the Mesh

cell of any system


Physics-aware meshing

• There are four physics preferences in the Meshing application, each using appropriate defaults for that physics


Meshing in batch

• Because the meshing is highly automated, the meshing application can be run in batch and a user can essentially skip the meshing step. For example:

For demonstration purposes we will use a Mesh system, but keep in mind any system could work in essentially the

same way.Create a geometry, or load an existing

geometry

The Geometry cell is checked off when the file is

attached

Use Update to generate the mesh

in batch,Status monitor gives progress

When meshing is complete, the Mesh cell is checked off, the user could

then proceed to the simulation setup, or Edit

the Meshing application to visualize the default mesh

Let’s view the default mesh in

the Meshing application


Parametric/Persistent meshing

• In the following slides, we will see how mesh methods and mesh controls can be inserted to control the properties of the mesh.

• These controls persist with any geometry changes.

• The process of updating the mesh is the same as in the batch meshing – Added controls continue to apply

– Well controlled mesh is automated for subsequent design iterations in batch

• This makes parametric/persistent meshing inherent to the process


Adding Controls for Flexibility

• As demonstrated, Meshing in Workbench is designed to be invisible to the user

• However, since a well controlled mesh is often required for higher solution accuracy and efficiency, there is a great deal of flexibility to control:

– mesh type/method– mesh sizing

– mesh alignment– mesh quality– mesh feature capturing


Adding Mesh Controls

• Let’s look at an assembly model:

Global controls: Physics preferences, sizings, inflation, etc.

• You can see in this case that Workbench automatically assigns:

• Physics based sizing

• Interfaces between parts

• User can go into these defaults and adjust as they see fit.

Contact is automatically

defined between parts

Mesh object: additional controls

can be inserted


Default meshing:

Sweepable parts can be

found/displayedSome parts are

meshed with general sweep

Some parts are meshed with

patch conforming tetrahedral method


• Mesh Methods:• Parts are meshed as

appropriate, hex where possible, else tets

• User can insert mesh methods to override the defaults.


To improve the mesh we can add

some mesh controls

Let’s see how we can coarsen mesh

in non-critical regions

Mesh is refined to respect each face

Grouped faces become

1 Virtual Face

Mesh walks over details


• Mesh Controls (Virtual Topology):

Virtual Topologies can be created

automatically, or manually as shown here.

• Geometry and mesh defeaturing tools are available to reduce the element/cell count in non-critical regions

• Manual virtual topologies help user control which features to capture


Let’s take a look at Automatic Virtual

Topologies.

Let’s hide all parts but the piston

Let’s examine ways to quickly

defeature this part

Mesh without Virtual Topogies

Automatic Virtual Topologies

Mesh after automatic

Virtual Topologies


• Mesh Controls (Auto VT):

Notice mesh ignores smooth boundaries but captures hard

boundaries

• Automatic virtual topologies can be created and then user can edit these manually for optimum control


Now let’s apply a body sizing to

improve uniformity of

mesh

Insert body sizing,

cross hatch represents

size

Resulting mesh


• Mesh Controls (Sizing):• Sizing controls are available

at the body, face, edge, and vertex level

• Other sizing controls include:

• Sphere of influence• Body of influence• Curvature/Proximity

sizing


Now let’s see if we can remove

some other small unwanted

features

Notice bad mesh in areasInsert manual pinch controls to remove unwanted features

Manual pinch feature removes features at mesh level allowing for easier simplification than geometry level

for some configurations. Like Automatic Virtual Topologies,

there is Automatic Pinch


• Mesh Controls (Pinch):• If Virtual Topologies (VTs)

aren’t enough for geometry simplification, pinch features can further simplify the model

• The pinch controls use mesh based defeaturing and can be applied manually or automatically like VTs.


The face mesh

structure can be changed by

adding mapped face

controls

Select face(s) to have a mapped

mesh

Face is meshed with

mapped quads split to tris


• Mesh Control (Mapped Face):

Since the face has a cutout, sub-mapping is done to get a mapped mesh


The bolt is an important aspect

of this model. Refining the mesh

and using hex elements will

improve results

Let’s look at just the bolt

Default tet mesh Hex mesh would improve solution

accuracy

Add Virtual Faces to aid in hex

meshing

Add MultiZone method for pure

hex meshPure hex mesh is

able to be generated

Apply body sizing with smaller mesh

size

Refined hex mesh for better accuracy

Section plane of hex mesh


• Mesh Methods and Controls:• This example shows how a

variety of mesh controls and methods can combine to provide great flexibility

• There is an extensive list of additional mesh methods/controls, but this gives a general overview of the use of these controls.


Adding Controls for Flexibility

• The controls that were added are stored as objects in the mesh folder

• These controls persist to design changes– If a new design makes it impossible to update controls

from a previous design, the software puts a ? to indicate a control that has become invalid and should be inspected by the user.


12.0 Feature Update12.0 Feature Update


R12 Meshing Goals

• Next generation solution for GAMBIT and CFX-Mesh customers:– Follows Workbench guiding principles:

Parametric, Persistent, Highly-Automated, Flexible, Physics-aware, Adaptive Architecture

• Integration of TGrid and ICEM CFD meshing methods to increase power and flexibility of Workbench meshing solution

• Further evolution of meshing tools and technologies for Mechanical, EMAG, Explicit and CFD meshing


Mesh controls

• Physics-based mesh controls• Support for CAD instances• Arbitrary mesh matching• Mapped mesh controls

– Corner controls to help define mapping strategy

• Pinch feature• Advanced Size Functions• Interface/contact handling between parts

– Contact sizing– Arbitrary mesh matching– Patch independent option: Match mesh where

possible


Fluids Physics-based

mesh controls

• R12 first release targeting Fluent needs using Fluent meshing components

• Better CFD meshing defaults:– Automated CFD meshing process

• CFD/Fluent shape check controls

– Support for FLUENT boundary conditions, mesh size functions, etc.

– Improved inflation controls • Program controlled inflation• Smooth transition controls


CFD Meshing

• Automated CFD meshing process:– CFX/Fluent solver preference added to tailor mesh

based off solver

– Added appropriate defaults– Added “Skewness” quality metric for FLUENT


CFD Meshing

• 3D Bodies (Zones) Solid/Fluid: – CAD parts can be marked in DM as Air/Fluid

– Display of Solid/Fluid indicates type– FLUENT will use this for 3D Zone creation

• 2D Zones– Named Selections (for Boundary Conditions) pass through

Workflow (CAD�Geometry�Meshing�FLUENT)


Improved CFD inflation

• Program Controlled Inflation: – Will inflate off all faces that are not in a named selection– Or user can inflate off a named selection, or insert inflation control


Structural Physics-based

mesh controls

• Efficient meshing for physics:

– Rigid body contact meshing• Edges/Faces in contact area are

only things meshed

• Centroid defined for mass

– Gasket meshing• Quadratic edges/faces on top and bottom • Linear edges/faces on side


Rigid Body Meshing (3D)

• Only faces of rigid body in contact get meshed


Rigid Body Meshing (2D)

• Only edges of rigid sheet in contact get meshed


Gasket Elements

• More automated way of meshing Gaskets

Quadratic faces on source/target

Linear faces on sides


Support for CAD Instances

• Instances defined in Pro/E, Solidworks, etc. are used in meshing (geometry/mesh is copied)– Geometry transfer/meshing speedup

• Selection by instance


Meshing of Instances

• Meshing speed improvement– 58% time reduction in meshing

• Instance selection:


Meshing of Instances

• Overall speed improvements1. Geometry transfer: 77% time reduction2. Meshing speedup: 55% time reduction3. Total import and meshing of this model reduced from

533 to 192 seconds (64% time reduction)


Arbitrary mesh matching

• Match control to copy mesh to similar topologies based off 2 coordinate systems


Improved Mapped Control

• Support for side/corner controls to define strategy for sub-mapping


Pinch Feature

• Mesh pinch out feature added for defeaturing at mesh level• Automated based off shell thickness or user defined tolerance

• Works in conjunction with Virtual Topologies to simplify meshing constraints


Automatic Pinch Generation

• With automatic pinch generation user can pinch features under a defined size and remove small features from the mesh

Use shell thickness, or define a tolerance


Manual Pinch Feature

• With Auto-pinch, software figures out basic areas to pinch• User can then add additional manual pinch controls


Shell Example

w/out pinch feature w/pinch feature


Shell Example



Solid Example



Advanced Size Function

• Incorporate Fluent size function

• Curvature based sizing controls • Proximity based sizing controls

• Body/Face/Edge sizing

• Improve consistency of controls across mesh methods



• Advanced size functions added for explicit control for:– Curvature Normal Angle

– Number of cells in a thin gap– Minimum Size

– Maximum Face Size– Maximum Tet Size– Growth Rate



• Standard Size Function

• Advanced Size Function



• With curvature

• With curvature and proximity (5 cells in gap)


Scoped sizes

• Scoped size controls:– Edge– Face

– Body


Body of influence

• Bodies can be used to define a region of influence


Interface/Contact modeling of parts

• There are several techniques to model the common faces between parts

– As parts– As multibody part with

common nodes

– As multibody part with duplicated nodes• Shared/matched face(s)• Shared/matched edge(s)



• There are several techniques to model the common faces between parts

– As parts– As multibody part with

common nodes

– As multibody part with duplicated nodes• Shared/matched face(s)• Shared/matched edge(s)

2 faces

1 face

2 faces



• As Parts:

– 2 Faces at contact region– Parts meshed separately



• As Multibody part:

– No contacts, since parts share common face

– Multibody part meshed as a whole

DM Attribute



• As Multibody part (w/Imprints):

– Contacts, since each body has a face

– Multibody part meshed as a whole

DM Attribute



• Depending on how the user wants the interface modeled/meshed between two bodies, user can choose appropriate option

• Using the imprint option in a multibody part ensures a common interface between 2 parts

• If using Imprint option, there are a few controls to keep in mind:– Contact sizing– Match control: Arbitrary– Patch independent option:

Match mesh where possible



• Contact Sizing– Drag and Drop Contact Region into Mesh folder

– Influences the mesh sizing between parts

Mesh isn’t always coincident



• Match Control: Arbitrary

– Enforces same node spacing based off common topology between parts

Undesired penetration of individual parts

Desired coincident nodes with multi-body part using IMPRINT method and Match control



• Patch Independent option: Match mesh where possible

– If “yes” software will try to enforce common nodes between common faces of a multibody(imprint) part

– If “no” software will not try to enforce common nodes between common faces of a multibody(imprint) part


Meshing ImprovementsMeshing Improvements


Surface meshing

• Improved surface mesh quality– Eliminate poor-quality mesh clusters

– Improved curvature based refinement controls

• 2D inflation controls

– 2D Planar models

– Shell models

• Respect new sizing controls

• Improved auto-blocker robustness/consistency


Meshing Update

More uniform surface mesh:R11 R12


Meshing Update

More uniform surface mesh:

R12

R11


2D inflation controls

• 2D planar model


2D inflation controls

• 2D shell model


Tetrahedral meshing

• Mix and Match Tetrahedral and Sweep methods

• TGrid Tetra AFT meshing method• Improved patch independent robustness

• Improved consistency of controls


Combination of methodsMapped bodies


Tetrahedral meshing

R11 R12


Inflation

• Refactor inflation for ease of use – best of what Fluent, CFX and ICEM CFD have to offer

• Improved Multibody part handling

• Smooth Transition • Collision avoidance:

– Stair-stepping – Layer compression

• Preview Inflation• Pre vs. Post inflation• Sweeping:

– Pure hex or wedge


Inflation: Multibody partsMapped bodies


Smooth Transition:

• Smooth Transition option added to provide layer by layer smoothing to achieve good transition to tet mesh

• Transition ratio controls inflation to tet transition

CFX Default Fluent Default


Inflation: Stair-stepping vs.

Compression

Layer Compression: Stairstepping:



Compression



Preview Inflation:

• Inflation preview added to help identify possible problems with inflation


Hex Meshing

• In Workbench there are several methods for hex meshing:– Default Sweep– Thin Sweep

– Hex Dominant

– MultiZone


Hex Meshing in R12

• R12 brings the following improvements: – Default Sweep

• Improved inflation

• More control over mesh type: quad, quad/tri, tri

– Thin Sweep• Support for body level (multibody parts)• Multiple elements through thickness for parts

– MultiZone• New option that extends all hex or hex dominant

meshing to more complex parts


Sweep: Inflation

• Inflation with sweeping generates a hex mesh


Sweep: Face mesh type

• Option for free face mesh type in sweep


Thin solid sweep meshing

• Improved robustness• Works at body level with other methods

Thin Sweep

General Sweep



• Multiple elements through thicknessfor single body parts



• Multibody part meshing


Swept meshing - MultiZone

• MultiZone sweep meshing– Automatic geometry decomposition– Multiple/single source/target

– Mapped/Free meshing

– Inflation


MultiZone

• Automatic geometry decomposition– With the sweep method, this part would have to be sliced into 5

bodies to get a pure hex mesh


MultiZone

• Automatic geometry decomposition– With MultiZone, this can be meshed with pure hex mesh without

any geometry decomposition.


MultiZone

• Multiple source imprinting– Imprints from multiple sources and cross sections can be swept


MultiZone

• Multi-source/multi-directional imprinting


MultiZone

• Multibody part handling– Multiple parts are meshed with conformal mesh at shared interface.


MultiZone: Multiple Zones

• Free decomposition– Face topology is used to construct solid regions or blocks.

Each block can be swept independently provided the mesh is conformal.


MultiZone: Free decomposition

• Using Free Mesh Type, MultiZone can be used to get a hex mesh where possible, and free mesh everywhere else, without slicing.


MultiZone: Free decomposition

• MultiZone unstructured/free regions can be filled with:

Free Mesh Type = Tetra

Free Mesh Type = Hexa Dominant

Free Mesh Type = Hexa Core


MultiZone with inflation

• MultiZone with inflation


MultiZone with inflation

• MultiZone with inflation and free blocks


Mesh Metrics

• Mesh metrics added– Mesh level, part level and body level

• Worst element display


Performance & Data-integration

Improvements

• Performance Improvements:– Multibody part mesh memory utilization & speed

improved

– General memory reduction and speed improvements

• Improved Data-Integration:– Named Selections stored to ACMO for use in CFX-Pre– Fluent output improved

– CGNS output added– Write ICEM CFD Files option for easier transfer to

ICEM CFD.


Thank you for your time!Thank you for your time!

r12 meshing feature presentation

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