Mesh-Intro-14.5-L07-Assembly-Meshing

©2012ANSYS,Inc.January15,20131Release14.514.5ReleaseIntroductiontoANSYSMeshingLecture7AssemblyMeshing©2012ANSYS,Inc.January15,20132Release14.5Whatyouwilllearnfromthispresentation•ConceptofAssemblyMeshing•AssemblyMeshingMethods–CutCell–Tetra•Controls•VirtualBodies•FluidSurfaces•Contacts•SharpAngleTool•LeakageAssemblyMeshing©2012ANSYS,Inc.January15,20133Release14.5PreprocessingWorkflowSketchesandPlanesGeometryImportOptions3DOperationsDirectCAD/Bi-DirectionalCADGeometryCleanupandRepairAutomaticCleanupMerge,Connect,Projection,FlowVolumeExtraction,etcExtrude,Revolve,Sweep,etc3DOperationsBoolean,BodyOperations,Split,etcMeshingMethodsHybridMesh:Tet,Prisms,PyramidsHexaDominant,SweepmeshingGlobalMeshSettingsLocalMeshSettingsSizing,Body/SphereofInfluence,MatchControl,etcGeometryCreationORGeometryImportGeometryOperationsMeshingSolverAssemblyMeshing©2012ANSYS,Inc.January15,20134Release14.5MeshingProcessinANSYSMeshing(AssemblyMeshing)©2012ANSYS,Inc.January15,20135Release14.5Behavior•Meshesanentiremodelassingleprocess–MeshMethodscoveredsofararepartorbodybasedmethods–Notcompatiblewithpart/bodymethods•TwoAlgorithmsavailable–CutCell&TetrahedronsAccess•AssemblyMeshingisaccessibleonlywhenPhysicsandSolverPreferencesaresettoCFDandFluentrespectively•Toactivate,replaceNonebyCutcellorTetrahedronsAssemblyMeshing©2012ANSYS,Inc.January15,20136Release14.5•Operatesonparts,multi-bodyparts,etc.–Toleratesoverlappingbodies•Createsconformalmeshesacrosspartsincontact–Eliminatestheneedformulti-bodypartgenerationinCAD•AbilitytodefineVirtualBodiesforfluidflowfroma“closed”setofbodies(sheetorsolid)–EliminatestheneedforBoolean/FilloperationsinCAD•PatchIndependent–EliminatestheneedforpinchcontrolandVToperations•MeshelementssizedrivenbySizeFunctionsAssemblyMeshing-CharacteristicsNotethatsomeglobalandlocalcontrolsarenotavailableforAssemblyMeshing(eg.MatchControl)CutCellAssemblyMesh©2012ANSYS,Inc.January15,20137Release14.5CutCellBehavior•CartesianmeshingmethoddesignedfortheANSYSFLUENTsolver•Generatesamajorityofhexcells–Somewedges,tetsandpyramidsatboundariestocapturegeometry–DuringtransfertoFluenthexacellsatsizetransitionareconvertedintoPolyhedra•SupportsInflation–Post-inflation(TGridalgorithm)•Inflationonzerothicknessbafflesnotsupported•Thickinflationlayersmayfail–Cutcellmeshgeneratedfirst,inflationgeneratedsecond(Post)AssemblyMeshing-CutCell©2012ANSYS,Inc.January15,20138Release14.5TetrahedronsBehavior•GeneratesaPatchIndependenttetrameshwithautomaticdefeaturing•Followingstepsoccurinbackground–GenerateCutCell–Deletevolumemesh–Triangulatesurfacemeshandimprove–Fillwithtetramesh•Compatiblewithinflation–Pre-inflation•AlgorithmsimilartoTetraPatchConformal•Hasthebenefitsofcutcell(norequirementonsolidbodies,patchindependent,etc)butwiththeflexibilityofthebottomupapproachi.e.“pre”inflationratherthanpostAssemblyMeshing-Tetrahedrons©2012ANSYS,Inc.January15,20139Release14.5•SetAdvancedSizeFunctions–ProximitySFSources:'edges',‘faces’or‘edgesandfaces’–‘Faces’isv.expensiveandedgesisrecommended–DefinecorrectMinSize(detailsnextslide)•InflationdefinedbyGlobalorLocalcontrols–CombinedGlobal&Localnotsupported–ProgramControlactsonFluidbodiesonly•BodiescanbesetasFluidinBodyproperties–ForVirtualBodies,onlyautomaticProgramControlledinflationcanbeused(wettedsurfacesmayonlybedefinedduringmeshing)•DefineFeatureandTessellationcontrols(seenextslide)•Applyanyrequiredlocalsizecontrols•Statistics–UseOrthogonalQualityforCutcellmeshesAssemblyMeshing-Controls©2012ANSYS,Inc.January15,201310Release14.5MinSizedefinition•AssemblyMeshingisPatchIndependentandstartswithaCartesianoverlaidgridwhichfindsclosedregions•Geometryrecoveryandleakagebetweenregionsdependonlocalsizes,i.e.ifCartesiansizeistoosmallnearagapyouwillgetleakagebetweenregions•LocalsizesaredrivenbySizeFunctiondefinitions–‘MinSize’and‘ProxMinSize’mustbesetwithcare–ProxMinSizecanbesmallerthanMinSizetoavoidover-refinementincurvedareas•Localmeshsizerecommendationtocapture3Dfeatures–Localsize½importantfeaturesize•Localmeshsizerecommendationtoclosegaps–1/10localmeshsizegapsize¼localmeshsize:applyhardsizingtoforcegapclosed–Gapsize1/10localmeshsize:gapclosedAssemblyMeshing-ControlsExample2.DoublingtheMinSizeclosesthegapExample1.MinSizetoolargecomparedtothesizeofthegeometricdetail©2012ANSYS,Inc.January15,201311Release14.5•FeatureCapture–ProgramControlled:defaultwhichsetsfeatureangle=40–FeatureAngle:userdefinedangletodefinefeatureleveltorecover•0tocaptureallcurvesinmodel•Tessellation(faceting)refinement–AssemblymeshingisappliedtoafacetedrepresentationofthegeometryviaTGridlibraries–ProgramControlled-defaultwhichsetstessellationrefinementto10%ofthevalueofsmallestmeshsize–AbsoluteTolerance–userdefinedtolerance•Mustbesetto5-10%ofsmallestmeshsize–None-SetstessellationtotheCADprogramorDesignModelerdefaultsetting•NoteDMfacetingcontrolisinOptionsGraphicsDesignModelerGraphicsFacetQualityAssemblyMeshing-ControlsTessellationproblemsmayleadtoleakage©2012ANSYS,Inc.January15,201312Release14.5•Imagesaboveshowthetessellatedrepresentationofthegeometr