FLUENT - Tutorial - Dynamic mesh - Missile Silo La

Tutorial:MissileSiloLaunchIntroductionThepurposeofthistutorialistoprovideguidelinestosetupandrunadynamicmesh(DM)caseusingthelayeringscheme.Thetutorialmodelsamissilebeinglaunchedfromasilo.Themotionofthemissileispredictedusingthesixdegreeoffreedom(6DOF)solverinFLUENT.Inthistutorial,youwilllearnhowto:•Readameshfileandperformadynamicmeshcalculation.•Enableandconfigurethe6DOFsolver.•CompileaUDFthatgovernsthemissilemotion.•Setupmovingzones.•Setupadynamicmesheventtocontrolthemeshmotion.•Definecustomcommandstobeexecutedatregularintervalsduringthesimulation.•Runanunsteadycalculationfortheproblem.•Writeimagefilesthatcanbeplayedasananimation.PrerequisitesThistutorialassumesthatyouarefamiliarwiththeFLUENTinterface,andthatyouhaveagoodunderstandingofthebasicsetupandsolutionprocedures.Inthistutorial,youwillusethedynamicmeshmodel.Ifyouhavenotusedthismodelbefore,refertoSection10.6:DynamicMeshesintheFLUENT6.2User’sGuide.ProblemDescriptionConsiderthelaunchofamissilefromitssilo(Figure1).The6DOFsolverisusedtopredictthemotionofthemissile.TheUDF(silo.c)isusedtospecifythepropertiesofthemissile(massandmomentsofinertia)aswellasanybodyforcesthatarepresent.The6DOFsolverappliesNewton’slawtodeterminetheaccelerationofthemissile.cFluentInc.March20,20061MissileSiloLaunchThrust,gravity,andpressureforcesareconsideredinthecalculation,whereasthedragonthemissileisneglected.Themissileenginestartstofireatt=0secondsbutthemissileisheldfixedinthesiloandisnotallowedtomoveuntilt=0.1seconds.Theflowisassumedtobeinviscidandthedomainisaxisymmetric.Figure1:ProblemSchematicofaMissileInsidetheSiloPreparation1.Copythefiles,silo.msh.gzandsilo.ctotheworkingdirectory.2.Startthe2D,double-precision(2DDP)versionofFLUENT.SetupandSolutionStep1:Grid1.Readthemeshfile,silo.msh.gz.File−→Read−→Case...2.Scalethegridtoinches.Grid−→Scale...(a)UnderUnitsConversion,selectinfromtheGridWasCreatedIndrop-downlist.(b)ClickScaleandclosethepanel.2cFluentInc.March20,2006MissileSiloLaunch3.Settheunitoflengthtoinches.Define−→Units...4.Checkanddisplaythegrid(Figure2).Display−→Grid...GridFLUENT6.2(2d,dp,segregated,lam)Feb10,2006Figure2:GridDisplaycFluentInc.March20,20063MissileSiloLaunch5.Settheviewsothatthemissilepointsupward(Figure3).Display−→Views...(a)ClickCamera....i.SelectUpVectorintheCameradrop-downlist.ii.SetXto1,Yto0,andZto0.iii.ClickApplyandclosetheCameraParameterspanel.Theviewupdatestoshowthemissilepointingupward.(b)UnderMirrorPlanes,selectaxis-inandaxis-out.(c)ClickApply.Theviewupdatestoshowthedisplaymirroredabouttheaxisofsymmetry.DonotclosetheViewspanel.(d)Zoomandpaninthedisplaytocentertheview(Figure3).(e)ClickSavetosavetheviewandclosetheViewspanel.Thesavedview,view-0appearsintheViewslist.6.Createzonesurfacesforthetwofluidzones.Surface−→Zone...(a)UnderZone,selectfluid-innerandclickCreate.(b)Similarly,createthefluid-outerzone.7.Displayfluid-innerzonesurface(Figure4).Thefluid-innerzonecontainsthemissileandismeshedwithquadrilateralelements.Thiszoneisboundedonthetopandbottomsidesbytheinteriorzonesinternal-topandinternal-bot,respectively.Thetaskistomovethisfluidzoneinaccordancewiththedynamicsofthemissile.Duringthisprocess,thelayeringalgorithmbuildslayersofquadrilateralelementsatinternal-botandcollapseslayersatinternal-top.Anon-conformalinterfacehastobeusedbetweenfluid-innerandfluid-outerzones,becausethefluid-innerzonewillmoverelativetotherestofthedomain.4cFluentInc.March20,2006MissileSiloLaunchGridFLUENT6.2(2d,dp,segregated,lam)Feb10,2006Figure3:RotatedandMirroredViewoftheGridGridFLUENT6.2(2d,segregated,lam)Mar17,2006Figure4:Thefluid-innerZonecFluentInc.March20,20065MissileSiloLaunchStep2:CompiletheUDFDefine−→User-Defined−→Functions−→Compiled...1.ClickAdd...andselectsilo.c.2.ClickBuild.TheInformationdialogboxisdisplayed.ReadtheinstructionscarefullyandclickOK.FLUENTcreatestheappropriatedirectorystructure,makefiles,andcompilesthecodeforyou.TheprogressofthecompilationisshownintheFLUENTconsolewindow.Youcanmonitortheprogressofthecompilationforanylinkingerrors.Alternatively,youcanalsoviewthelogfilewiththecompilationhistorythatwillbecreatedintheworkingdirectory.3.ClickLoad.Step3:Models1.EnabletheCoupledsolverwithExplicitformulation,Unsteadytimecondition,andAxisymmetricspace.Define−→Models−→Solver...6cFluentInc.March20,2006MissileSiloLaunch(a)SelectCoupledunderSolver,ExplicitunderFormulation.(b)SelectAxisymmetricunderSpace,andUnsteadyunderTime.Dynamicmeshfeaturesareavailableonlyintheunsteadysolverwithfirst-orderimplicittimediscretization.(c)RetainthedefaultsettingsfortheremainingparametersandclickOK.2.EnabletheEnergyequation.Define−→Models−→Energy...3.EnabletheSpalart-Allmarasturbulencemodel.Define−→Models−→Viscous...(a)UnderModel,selectSpalart-Allmaras(1eqn).(b)RetainthedefaultsettingsfortheotherparametersandclickOK.4.EnabletheSpeciesTransportmodel.Ithelpsyouindistinguishingbetweenairandexhaustgases.Define−→Models−→Species−→Transport&Reaction...(a)UnderModel,selectSpeciesTransport.(b)ClickOK.cFluentInc.March20,20067MissileSiloLaunchStep4:Materials1.Createanewfluidmaterialnamedexhausttorepresenttheexhaustgasesofthemis