gambit-23-Lecture-06a--VolumeMeshing

6-1FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006VolumeMeshing6-2FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006ApproachAhigh-qualityhexmeshisgenerallypreferredoveratetmesh.Reduceddiscretizationerrorandfalsenumericaldiffusionforagivenmeshsize.SignificantlylowercellcountExample:Comparethecellcountfora10×10×10cubeusinghexandtetwithacellsizeof1.Hexmeshgenerates1,000cells.Tetmeshgenerates7,726cells!Forahexmesh,geometriestypicallyneedtobedecomposedintosimpleronessothatoneofthehexmeshingschemescanbeused.Insomecases,thegeometrycanbeverycomplex.Hexmeshingcanbeexpensiveorimpractical.Inthesecases,atetorhybridmeshispreferredinordertoreducemeshingeffort.6-3FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006VolumeMeshingUponpickingavolumeGAMBITwillautomaticallychooseatypebasedonthesolverselectedandthecombinationofthefaceTypesofthevolume.Inambiguouscases,GAMBITchoosestheTet/Hybrid:TGridcombinationAvailableelement/schemetypecombinationsHexMap,Submap,TetPrimitive,Cooper,StairstepHex/WedgeCooperTet/HybridTGrid,HexCore6-4FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006VolumeMeshes-HexExamplesHex–MapHex--SubmapHex–TetPrimitiveHex–Cooper6-5FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006Hex/WedgeandTet/HybridExamplesHex/Wedge:CooperTet/Hybrid:TGridTet/Hybrid:HexCore6-6FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006HexMeshing–MapAmappablevolume:IsalogicalcubeHasallfaceseithermappableorsubmappableHastopologicallymatchingmeshonallfaces.MeshMeshsubmapface6-7FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006HexMeshing–SubmapAsubmappablevolume:Hasallfaceseithermappableorsubmappable.Hastopologicallymatchingoppositefaces.MeshMesh6-8FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006HexMeshing–TetPrimitiveTet-PrimitiveschemeAllhexelementsinafour-sided(tetrahedral)volumeVolumesdirectlymeshableusingTetPrimitiveschemeHowthetetprimitiveschemeworksConnectcenterpointsonedges,facesandthevolumeMeshthefoursubvolumesusingthemapscheme.Mesh6-9FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006HexMeshing–CooperTheCooperschemeprojectsorextrudesafacemesh(orasetoffacemeshes)fromoneendofavolumetotheotherandthendividesuptheextrudedmeshtoformthevolumemesh.TheprojectiondirectionisreferredtoastheCooperdirection.Facestopologicallyperpendiculartothisdirectionarecalledsourcefaces.Sourcefacesneednotbepremeshed.Atleastonesourcefacemustnotbemeshedandmustspantheentirecrosssection.Facesthatintersectthesourcefacesarereferredtoassidefaces.SidefacesmustbeeithermappableorsubmappableSideFaces(twohidden)CooperdirectionSourceFaces6-10FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006CooperExamplesVolumeContainingMultipleHolessourcefacessourcefacessourcefacesSourceFacesNotParallelsourcefacesMultipleSourceFacesandMultipleInteriorLoops6-11FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006CooperToolMethodologyWhentheCooperschemeisselected,asourcefacelistboxappearsinthepanel.IfGAMBITchoosesthesourcesfacesCheckthesourcefacelistandverifythatGAMBIThaschosenthecorrectfaces.Ifnecessary,changethesourcefacesselection.GAMBITmaynotbeabletoresolvethesourcefacesManuallyselectthesourcefacesIfnecessary,manuallychangethevertextypes(discussedinlecture3)onsomeofthesidefaces6-12FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006TroubleshootingtheCooperToolABCProblem:SourcefacesA,B,andCarepremeshed.TheCoopertoolfails.Why?Howcanthisvolumebemeshed?6-13FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006TroubleshootingtheCooperToolSolution:ThemeshonsourcefacesAandBcannotbeprojectedontofaceC(thesourcefacesareoverconstrained.DeletethemeshonfaceCinordertogeneratethevolumemesh.ABC6-14FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006TroubleshootingtheCooperToolProblem:Abrickissplitasshown.TheCoopertoolfails.Why?Whatcanbedonetogenerateavolumemesh?ABC6-15FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingGAMBIT2.3June2006TroubleshootingtheCooperToolSolution:Coopertoolfailsbecausenologicalaxisexists.IffacesAandBaresourcefaces,thenfaceCmustbeeithermappableorsubmapple.FaceCcontainsavoidandcanonlybepaved.Splitthevolumewithafaceasshown.UseFaceA1asonesourcefaceforvolume1andusefaceC2asonesourcefaceforVolume2.A1Volume1Volume2C1ABC6-16FluentUserServicesCenterwww.fluentusers.com©2006FluentInc.IntroductoryGAMBITTrainingG