Download - Ask-The-experts ANSYS Advanced Meshing

8/13/2019 Ask-The-experts ANSYS Advanced Meshing

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2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary


Advanced Meshingin ANSYSMechanical

Govindan Nagappan


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umm ry

Meshing FrameworkImprovements

Direct meshing

Parameter handling

Improved Virtual Topologies

Mesh-based Connections

Improved Named Selections

Mesh Controls

Advanced Size Function

Body of Influence

Mesh Based Defeaturing

Improved Mapped Meshing

Pinch Control

Mesh Methods

Improvements in Shell meshing

Improvements in Hex meshing

Sweep

MultiZone meshing


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Direct Meshing

ANSYS Workbench meshing has been focused onautomated meshing:

Software automates choice of methods, physicsdefaults and controls

Interaction between methods is automated

At 13.0, the user has greater access to directlymesh bodies of multibody parts:

This provides more flexibility and control over themeshing process

Control the meshing sequence


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Direct Meshing

Direct Meshing advantages: Bodies can be meshed individually

Mesh seeding from meshed bodies influence

neighbors (user has sequence control)

Automated meshing can be used at any time to

finish rest of meshing (control where you want it

while keeping the automation)

When controls are added, only affected bodymeshes go out of date

More extensive mesh method interoperability


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Direct Meshing: Local Meshing

Individual bodies can be meshed (no need forsuppression as in 12.1)

Subsequent bodies use the attached face mesh

Direct Meshing allows for more combinations of how to handle the

common interface between bodies


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Direct Meshing: Local Remeshing

Automated meshing:

Mesh methods and orderdefined automatically

Good starting mesh

Direct meshing: On inspection, would like

more mesh in some spots:

Add method, inflation or

sizing control and upon

Generate Mesh, only this

body (and any affected

bodies) are re-meshed


7/47 2010 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary

Direct Meshing: Selective Body

Updating

Similarly if only part of the geometry changes: Only affected bodies need

to be updated/remeshed

Significant time savings

on model change

Face Delete in DM

Geometry Refreshonly 1 body is out of date

Generate meshonly 1 body is meshed



Direct Meshing: State

Management

State management: The part/body tree willindicate which bodies need to be remeshed:State icons indicate status of bodies.

When mesh controls are added you will

notice that the state changes, even

though the mesh remains visible.

Body meshes can be generated or

cleared at body level.Generate mesh at mesh level will

generate the mesh for all unmeshed

bodies



Direct Meshing: Ordered Meshing

Automated meshing

Layer of tet

mesh required

as topology

changes

Direct meshing

With Direct Meshing:

Mesh thin sweep first,then mesh rest of model with

Automated meshing

Direct meshing complements the

automated meshingThin Sweep Mesh Method can handle this, but the

order the mesh is generated in is critical


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Parameterization in ANSYS

Meshing

Meshing controls can now be parameterized

Global controls and local controls Selection of parameter promotes the parameter to the WB project page

Geometry and Meshing parameters can be related using expressions in the parametermanager

New in AM 13.0!



Parameterization Project Example

Number of divisionson the outlet pipe

equal to two times its

length

Number of divisons

on the inlet pipe equal

to its length + 4

8+4=12d

ivisions

Inlet

Outlet



Parameterization Project Example

(Cont)



When to use?

To merge together a number of small (connected) faces/edges To simplify small features in the model

To simplify load abstraction for mechanical analysis

To create edge splits for better control of the surface mesh control New in AM13.0!

Virtual cell modifies the topology

Original CAD model remains unchanged New faceted geometry is created with

virtual topology

Virtual Topology

Without VT With VT



Edge Splits to Guide Meshing

VT edge splitsavailable to help

guide meshing:

Edge splits introduced to

constrain the mapped mesh

Difficult to get a good mesh

with complex wavy curves

Mesh is improved

Edge splits can be further

moved interactively



Mesh connections

For sheet models, connections can be defined asMesh connections

Options include similar options as other connections

Mesh connections will be created at mesh time (rather

than as CE in solver)



Mesh Connections

Create Automatic Connections Automatic connections are created

Displays result from

mesh connections



Mesh Connections

After meshing, user can also look at mesh connectivity

Automatic connections are created



Named Selections

Named Selections allow users to assign aname to one or more selected entities in DMor AM

The Named Selections used in DM can betransferred to AM by allowing in the Workbenchoptions (Tools/Options/Geometry Import) beforeopen a DM session

All entities within a Named Selection must be ofthe same topology

Easy to reselect groups that will be referencedoften

Named selections are automatically exported tosolver modules

Named Selections can be applied to the entitiesof the same size, type or location, by usingnew selection options New in AM 13!. See the

Appendix at the end for details

Named Selection groups can be imported from DesignModeler

and other CAD systems



Enhanced - Named Selections

New option to define selection by worksheet

Worksheet allows set of actions to build up anamed selection based on a criteria(size,

location, type, coordinate system, convert etc.

Able to quickly define criteria whencreating from Graphics Window



Named Selections

Named Selections can be applied to selected geometries Named Selections can be applied to a set of entities of thesame size, location or type by using the filterApply geometry

items of same

804 faces selected in

one click!New in AM13!



Sizing : Advanced Sizing Function

ASF : Off

Only edge sizes are

determined based on

curvature and are

controlled by the span

angle center Rest of the mesh is

generated with global

element size

Curvature or proximity is

not considered for face

and volume meshing

ASF : Curvature

Determines the Edge and

Face sizes based on

Curvature Normal Angle

Curvature Normal Angle

is the max angle b/wadjacent Face normals

Finer Curvature Normal

Angle creates finer surface

mesh


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Sizing : Advanced Sizing Function

(Contd)

ASF : Proximity & Curvature

Combines the effect of

Proximity and Curvature

size function

More computational

time due to combined

effect of Curvature and

Proximity

ASF : Fixed

Constant mesh size through

out

No refinement due to

curvature or proximity in the

model

Surface mesh is generated

with specified Max Face Size

Volume mesh is generated

with specified Max Size

ASF : Proximity

Controls the mesh

resolution on proximity

regions in the model

Fits in specified numberof elements in the narrow

gaps

Higher Number of Cells

Across Gap creates more

refined surface mesh


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Bodies of influence (BOI)

Lines, surfaces and solid bodies can be used to refine the mesh

Accessible when ASF is On

The Body of Influence itself will not be meshed

Sizing : Bodies of Influence

Line BOIs

Surface BOI Solid BOI

Without BOIs


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Baffle Surface

2 layers created with baffle surface

Without baffle surface

Use of Baffle surface to ensure atleast

2 layers of thickness on a thin model

meshed with tetra


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Inflation

Add more layers through thickness of a thinmodel that cannot be meshed with sweep


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Defeaturing

Removes small geometry features meeting the tolerances

using Pinch or/and Automatic Mesh Based Defeaturing

controls in order to improve the mesh quality. Not all

meshing methods can take advantage of these controls

Pinch Tolerance control removes small features at the

mesh level depending on the Pinch Tolerance value

provided. ANSYS Meshing offers global and manual pinch

controls

Automatic Mesh Based Defeaturing (AMBD) when it is On

features smaller than or equal to the value of Defeaturing

Tolerance are removed automatically

AMBD Off AMBD On With Pinchs


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Pinch

Pinch control removes small features (edges or narrowregions) at the mesh level

The Pinch feature works on vertices and edges only. Faces

and bodies cannot be pinched

The Pinch feature is supported for the following mesh

methods: Patch Conforming Tetrahedrons

Thin Solid Sweeps

Hex Dominant meshing

Quad Dominant Surface Meshing

Triangles Surface meshing


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Vertex-vertex Pinch controls will be created on an edge with

length less than the specified tolerance

Will pinch out the slavegeometry into the master

geometry

Pinch: Vertex-Vertex

Mesh without Pinch

Control

Mesh with Pinch

Control


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Edge-Edge Pinch controls will be created on any face for

which two edges are within the proximity of specifiedtolerance

Will pinch out the entire or aportion of the slave geometry into

the master

Pinch: Edge-Edge

Mesh without Pinch

Control

Mesh with Pinch

Control


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Connectivity Repair Tools

DM: Automatic extensions

Mechanical/Meshing: Pinch controls

Quickly connect sheet models

On closer inspectionCleanup of geometry

can be manual, due

to tolerances.Use pinch controls to

quickly fine tune

models


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Side, Corner and End controls for vertices, to define strategy for Mapping

Vertex Type Intersecting Grid Lines Angle Between EdgesEnd 0 0 135

Side 1 136 224

Corner 2 225 314

Mapped Face Meshing: Vertex

Type


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Mapped Face Meshing: Example

Appropriate definition of vertices and edge grading

results in a good structured mesh

E

E

E

E E

EE

S

E

E

E

S


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If face is defined by two loops, then the Radial Number of Divisions field

is activated

Specify the number of divisions across the annular region

Useful for creating number of layers across an annulus

Mapped Face Meshing: Radial No.

of Divisions

Mapped face is swept to create

pure hex mesh


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More automated mapped mesh

Option to find mappable faces:

These faces can be put into a mapped face control to

provide better guidance for mesher


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Shell Modeling Improvements

Seam welding Edge/Mesh connectivity display

Mesh connections

Edge/Face pinch controls

Displays result from mesh

connections


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Improved Default Surface Mesh

Default surface mesh improvements: advanced size functions to improve

mesh transitions and orthogonality

12.1 Defaults

13.0 Defaults


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Shell Meshing: Example

New in AM 13.0!

Edge colored by the number of connected faces

Automatic generation of mesh connections

Mesh connectivity can be shown also after meshing

Ability to find mappable faces


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Surface Meshing with Inflation

Quad mesh with Inflation Inflation can be applied on theselected edges or named selections

New in AM 13.0!


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Sweep Meshing

Example:

Src/Trg Selection - Rotational sweep for sector like geometry

Sweep Mesh: Wedgeand Hex elements

Sweepable bodies

Manual Selection

Target Face

Source Face


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Sweep Meshing

Example:

Src/Trg SelectionAutomatic Thin

Sweepable BodyMultiple source faces

Thin Sweep MeshAutomatic ThinSelection

For multibody parts only one sweep number of divisions is

allowed for Automatic or Manual Thin sweep method


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Need for Multizone

The MultiZone mesh method is a new meshing method

introduced in ANSYS 12.0 to extend sweeping capabilities to alarger range of problems:

Limitations with Sweep Method:

Only Single Source to Single Target

Requires geometry decomposition for multiple sweep paths

No defeaturing within Sweep method

High memory requirements

Can only inflate source face


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Based on blocking approach used in ANSYS

ICEM CFD Hexa Automatically decomposes geometry

Uses structured and unstructured blocks

Can have multiple source and target faces

Depends on settings of Free Mesh Type

Structured blocks are meshedwith Hexa or Hexa/Prism

If Free Mesh Type is set to other than Not Allowed thenunstructured blocks are meshed

with Tetra, Hexa Dominant or Hex Core based on the selectedmethod

Program Controlled inflation Newin AM13.0!

MultiZone Meshing

MultiZone Mesh


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MultiZone Meshing

Control:

Src/Trg Selection - Automatic

Details View of

MultiZone MethodGeometry for MultiZoneMeshing MultiZone Mesh


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MultiZone Meshing

Control:

Src/Trg Selection - Manual

Details View of

MultiZone Method

Geometry for MultiZoneMeshing

Cut section of MultiZoneMesh


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MultiZone improvements

Program Controlled Inflation

With default of smooth transition inflation