fluent 7文档格式.docx

fluent 7文档格式.docx

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SolvethisproblemusingFLUENT.Plotthecenterlinevelocity,wallskin-frictioncoefficient,andvelocityprofileattheoutlet.Validateyourresults.

Note:

Thevaluesusedfortheinletvelocityandflowpropertiesarechosenforconvenienceratherthantoreflectreality.ThekeyparametervaluetofocusonistheReynoldsno.

PreliminaryAnalysis

Weexpecttheviscousboundarylayertogrowalongthepipestartingattheinlet.Itwilleventuallygrowtofillthepipecompletely（providedthatthepipeislongenough）.Whenthishappens,theflowbecomesfully-developedandthereisnovariationofthevelocityprofileintheaxialdirection,x（seefigurebelow）.Onecanobtainaclosed-formsolutiontothegoverningequationsinthefully-developedregion.YoushouldhaveseenthisintheIntroductiontoFluidMechanicscourse.Wewillcomparethenumericalresultsinthefully-developedregionwiththecorrespondinganalyticalresults.Soit'

sagoodideaforyoutogobacktoyourtextbookintheIntrocourseandreviewthefully-developedflowanalysis.Whatarethevaluesofcenterlinevelocityandfrictionfactoryouexpectinthefully-developedregionbasedontheanalyticalsolution?

Whatisthesolutionforthevelocityprofile?

We'

llcreatethegeometryandmeshinGAMBITwhichisthepreprocessorforFLUENT,andthenreadthemeshintoFLUENTandsolvefortheflowsolution.

GotoStep1:

CreateGeometryinGAMBIT

Step1:

Ifyouwouldprefertoskipthemeshgenerationsteps,youcancreateaworkingdirectory（seebelow）,downloadthemeshfromhere（rightclickandsaveaspipe.msh）intotheworkingdirectoryandgostraighttostep4.

StrategyforCreatingGeometry

Inordertocreatetherectangle,wewillfirstcreatetheverticesatthefourcorners.We'

llthenjoinadjacentverticesbystraightlinestoformthe"

edges"

oftherectangle.Lastly,we'

llcreatea"

face"

correspondingtotheareaenclosedbytheedges.InStep2,we'

llmeshthefacei.e.therectangle.Notethatin3Dproblems,you'

llhavetoforma"

volume"

fromfaces.SothehierarchyofgeometricobjectsinGAMBITisvertices->

edges->

faces->

volumes.

CreateaWorkingDirectory

Createafoldercalledpipeinaconvenientlocation.We'

llusethisastheworkingfolderinwhichfilescreatedduringthesessionwillbestored.

NoteforACCELcomputerlabusers:

Eachusergetshis/herown100MBofdiskspaceunderS:

atACCEL.YoucanputyourfilesinS:

andit'

llbeaccessiblefromanycomputer.Thisiswhereyoushouldputfilesthatyouwanttokeepandaccesslateron.

StartGAMBIT

Startyourcommandprompt.

Start>

Run

InWindowsNT/2000/XP:

Typecmdandpressenter.

InWindows95/98/ME:

Typecommandandpressenter.

Navigateyourwaytoyourworkingfolder.Forexample,ifyoucreatedafoldernamedfluentondriveS:

inWindows,typecdS:

\fluentatthecommandpromptandpressEnter.

StartGAMBITbytypinggambit-idpipeatthecommandpromptandpressingEnter.

Ifthisdoesn'

twork,trytypingthefullpathnametotheGAMBITexecutable:

c:

\fluent.inc\ntbin\ntx86\gambit-idpipe

ThisbringsuptheGAMBITinterfaceandtellsGAMBITtousepipeasthedefaultprefixforallfilescreatedduringthesession.InWindows,theExceedX-serverstartsupbeforetheGAMBITinterfacecomesup.Exceedisathird-partyapplicationneededtorendertheinterfaceinWindows（GAMBITwasoriginallydevelopedunderUnix）.Tomakebestuseofscreenrealestate,movethewindowsandresizethemsothatyouapproximatethisscreenarrangement.ThiswayyoucanreadinstructionsinthebrowserwindowandimplementtheminGAMBIT.

Youcanresizethetextinthebrowserwindowtoyourtasteandcomfort:

InInternetExplorer:

Menubar>

View>

TextSize,thenchoosetheappropriatefontsize.

InNetscape:

IncreaseFontorMenubar>

DecreaseFont.

TheGAMBITInterfaceconsistsofthefollowing:

∙MainMenuBar:

NotethatthejobnamepipeappearsafterID:

inthetitlebaroftheUtilityMenu.

∙OperationToolpad:

llmoreorlessworkourwayacrosstheOperationToolpadaswegothroughthesolutionsteps.Noticethataseachofthetopbuttonsisselected,adifferent"

sub-pad"

appears.TheGeometrysub-padisshownintheabovesnaphot.

∙GlobalControlToolpad:

TheGlobalControlToolpadhasoptionssuchasFittoScreen

andUndo

thatareveryhandyduringthecourseofgeometryandmeshcreation.

∙GAMBITGraphics:

Thisisthewindowwherethegraphicalresultsofoperationsaredisplayed.

∙GAMBITDescriptionPanel:

TheDescriptionPanelcontainsdescriptionsofbuttonsorobjectsthatthemouseispointingto.MoveyourmouseoversomebuttonsandnoticethecorrespondingtextintheDescriptionPanel.

∙GAMBITTranscriptWindow:

ThisisthewindowtowhichoutputfromGAMBITcommandsiswrittenandwhichprovidesfeedbackontheactionstakenbyGAMBITasyouperformoperations.If,atsomepoint,youarenotsureyouclickedtherightbuttonorenteredavaluecorrectly,thisiswheretolooktofigureoutwhatyoujustdid.YoucanclickonthearrowbuttonintheupperrighthandcornertomaketheTranscriptwindowfull-sized.Youcanclickonthearrowagaintoreturnthewindowtoitsoriginalsize.Goahead,givethisatry.

SelectSolver

SpecifythatthemeshtobecreatedisforusewithFLUENT6.0:

MainMenu>

Solver>

FLUENT5/6

VerifythishasbeendonebylookingintheTranscriptWindowwhereyoushouldsee:

Theboundarytypesthatyou'

llbeabletoselectinthethirdstepdependsonthesolverselected.

Wecanassumethattheflowisaxisymmetric.Theproblemdomainis:

whererandxaretheradialandaxialcoordinates,respectively.

Strategyforcreatinggeometry

Wewillputtheoriginofthecoordinatesystematthelowerleftcorneroftherectangle.Thecoordinatesofthecornersareshowninthefigurebelow:

Wewillfirstcreatefourverticesatthefourcornersandjoinadjacentverticestogettheedgesoftherectangle.Wewillthenformafacethatcoverstheareaoftherectangle.

CreateVertices

FindthebuttonsdescribedbelowbypointingthemouseateachofthebuttonsandreadingtheDescriptionWindow.

OperationToolpad>

GeometryCommandButton

>

VertexCommandButton

CreateVertex

NoticethattheCreateVertexbuttonhasalreadybeenselectedbydefault.Afteryouselectabuttonunderasub-pad,itbecomesthedefaultwhenyougotoadifferentsub-padandthencomebacktothesub-pad.

Createthevertexatthelower-leftcorneroftherectangle:

Nexttox:

entervalue0.Nexttoy:

entervalue0.Nexttoz:

entervalue0（thesevaluesshouldbedefaults）.ClickApply.Thiscreatesthevertex（0,0,0）whichisdisplayedinthegraphicswindow.

IntheTranscriptwindow,GAMBITreportsthatit"

Createdvertex:

vertex.1"

.Theverticesarenumberedvertex.1,vertex.2etc.intheorderinwhichtheyarecreated.

Repeatthisprocesstocreatethreemorevertices:

Vertex2:

（0,0.1,0）

Vertex3:

（8,0.1,0）

Vertex4:

（8,0,0）

Notethatfora2Dproblem,thez-coordinatecanalwaysbelefttothedefaultvalueof0.

GlobalControl>

FittoWindowButton

ThisfitsthefourverticesoftherectanglewehavecreatedtothesizeoftheGraphicsWindow.

（Clickpictureforlargerimage）

CreateEdges

llnowconnectappropriatepairsofverticestoformedges.ToselectanyentityinGAMBIT,holddowntheShiftkeyandclickontheentity.

EdgeCommandButton

CreateEdge

SelecttwoverticesthatmakeupanedgeofthisrectanglebyholdingdowntheShiftbuttonandclickingonthecorrespondingvertices.Aseachvertexispicked,itwillappearredintheGraphicsWindow.ThenletgooftheShiftbutton.Wecanchecktheselectedverticesbyclickingontheup-arrownexttoVertices:

.

Thiswillbringupawindowcontainingtheverticesthathavebeenselected.VerticescanbemovedfromtheAvailableandPickedlistsbyselectingthemandthenpressingtheleftorrightarrowbuttons.

Afterthecorrectverticeshavebeenselected,clickClose,thenclickApplyintheCreateStraightEdgewindow.

Repeatthisprocesstocreatearectangle.

（Clickpictureforlargerimage）

CreateFace

FaceCommandButton

FormFace

Toformafaceoutoftheareaenclosedbythefourlines,weneedtoselectthefourledgesthatenclosethisarea.ThiscanbedonebyholdingdowntheShiftkey,clickingoneachline（noticethatthecurrentlyselectedlineappearsred）,andthenreleasingtheShiftkeyafterallfourlineshavebeenselected.

Alternatively,aneasierwaytodothiswouldbetoclickontheuparrownexttoedges:

ThiswillbringuptheEdgeListwindow.ClickonAll->

toselectalloftheedgesatonce.ClickClose.

ClickApplytocreatetheface.

GotoStep2:

MeshGeometryinGAMBIT

Step2:

MeshGeometryinGAMBIT