ICEM-CFD Advanced Tetra Part III Hybrid Meshing

27February2020Tetra1AdvancedTetraHalfDayPartIIIHybridMeshing27February2020Tetra2ConcatenateTetinfilesandDomainfilesLoad(concatenate)bothtetinfilesanddomainfiles.27February2020Tetra3MergedMeshDeletevalvematerialpoint,replacewithorfnmaterialpoint.Twodomainsaremerelysuperimposed,notactuallyjoined(madeconsistent).Savemergeddomainandtetin,exitandrestartICEMCFD,oritmaycrash.Thisbughasbeenfixedin4.227February2020Tetra4MakeConsistentTheMakeconsistentcommandactuallymakesthevolumemeshconsistentwiththesurfacemesh.27February2020Tetra5ApartialsuccessDuetothecomplexitiesinvolved,severalsurfaceelementswerecorruptedandthevolumeleaked.Themeshisnowconsistent,justre_runthecuttertoremovetheinternalelements.27February2020Tetra6Re-runCutterTheMergeddomainreplacesthe“uncut_domain.1”TheCutterrunsinasmallfractionofthetimerequiredtore-meshthevolume27February2020Tetra7RotateValveGeometryTocreateamodelofanothervalveposition,simplyrotatethevalveandre-concatenate/makeconsistentwiththeductmesh.27February2020Tetra8RotateValveSurfaceMeshThegeometryandmesharerotatedseparately.27February2020Tetra9RotatedValveValveisreadytobeinsertedintothemesh.27February2020Tetra10ConcatenateddomainsandtetinfilesBothdomainssharethesamevolume,butarenotconnected.27February2020Tetra11MakeConsistentThetwodomainsarenowmergednodefornodeThistime,therewerenoproblemsandtheinteriorcutoutproperly.27February2020Tetra12SmoothSincetheresultingmeshisstilljusttetra_4andtri_3elements,itisrelativelyeasyforthesmoothertoimprove.Tetraqualityabove0.2isgoodforallthemajorsolvers,thoughotherqualitymetricsmayalsobeimportant.Tofindtheminimumsyouneed,checktheinformationthatcamewithyoursolver.27February2020Tetra13PrismPreparationHybridmeshisgenerallydifficulttosmooth.Thebestwaytogetagoodprismmeshistostartwithagoodtetrameshandchooseyourprismoptionscarefully.Alittlepreparationwillsavealotoftimelater.Herearesomegoodsuggestions:Makesureyoustartoutwithagoodqualitytetramesh.Notonlyaspectratios,butcheckandfixalldiagnostics-single/multipleedges,non-manifoldverticesandduplicateelementswillcrashtheprismmesher.It'sagoodideatovisuallyscanthesurfacemeshaswell.Lookforkinksorsharptentlikestructuresinthemesh.Thediagnosticsmaynotfindthese.Youshouldmanuallyfixanysurfacediscrepancies.Anotherimportantthingistomakesurethefamilyassociationiscorrect.Sometimesyoumayseeafewelementsinonefamilyscatteredamongstsomeotherfamily.Thismayalsocauseprismtocrashespeciallyifyou'rejustextrudingfromafewisolatedelementsandnoneofit'sneighbors.Youcanalwayschangethefamilyofthemeshtofixisolatedelements.AgoodtooltofindisolatedelementsisDiagnostics-Possibleproblems-Familyboundaryedges.27February2020Tetra14PrismprocessStartsfromICEMCFDTetrameshBatchprocessGeneratesPrism(pentahedral)elementsnearboundarysurfacesPrismscreatedbyextrusionofsurfacemeshPrismsaremadeconformalwithtetrahedralvolumemeshSmoothingyieldsnecessaryquality27February2020Tetra15PrismFileinformationPick3,Calculate4th,fastertomesh1layerandsplitit.Totalheightshouldbelessthan1/3ofthesmallestgapdistanceforthatsurfaceRatherthangobelowthis,themeshwillWalkawayfromthewall,useifyouhavesharpcorners,0.05iscommonOnthismodel,filletisnotgoodnearthecuspareasAssigningthesefamilieswillhelpwithvisualizationlaterDiscussedlaterDiscussedinalaterslideFor1layer,morethanonestepisnotneededTheseHaveAerodynamicsApplications27February2020Tetra16MinprismqualityRatherthangrowpoorelementsinthecusp,themeshwouldrather“walkaway”fromthewallThistendencyiscontrolledbythe“MinprismqualityUsually,asettingof0.05isgood.27February2020Tetra17PrismOptions–FilletRatioBlendsprismgridlinesaroundsharpcorners0=nofillet1=filletradiusequalsprismheightFilletRatio=0.0FilletRatio=0.5FilletRatio=1.0Ifyouaremeshingtightspaceswithtightcurves(Lessthan60º),youmaynothavespaceforafiletratio.27February2020Tetra18PrismOptions–MaxPrismAngleallowsprismlayerto‘detach’fromadjacentsurfacesEdgeofprismlayeriscappedwithpyramidsUsuallysetthistotherangeof120to180degreesOriginalmeshMaxprismangle=180deg.Maxprismangle=140deg.Learningtosetthiswillcomewithexperience.Ifyouextrudefromonefamilyandnotit'sneighborandtheanglebetweenthesetwofamilysurfacesisgreaterthanthisvalue,itwillcapoffthequadsideoftheprismwithapyramid.Thisistoavoidbendingtheprismallthewaytotheboundary(familynotextrudingfrom)thatwouldcreatebadinternalangles.Ontheotherhand,sometimesthosepyramidsareabiggerproblem.27February2020Tetra19ToRestrictPrismAspectRatioPrismheightlimitfactorRestrictsaspectratioofnewprismstosetvalueGrowsspecifiednumberoflayersWillfailifthecellsizesonadjacentelementsdifferbymorethanafactorof2.Limitfactor=0.5Limitfactornotset27February2020Tetra20ToRestrictPrismAspectRatioMaxheightoverbaseStopsgrowingprismsifaspectratioexceedssetvalueMeshismadeconsistentusingpyramidsOftenitisdifficulttosmooththeresultingmeshMaxheightoverbase=0.5Maxheightoverbasenotset27February2020Tetra21PrismThebottomportionofthePrismformallowstheusertotoadjusttheprismlayergrowthbasedonFamilies.UsingEditMesh=Changefamily,theusercanchangethefami