层流管道Word文件下载.docx

层流管道Word文件下载.docx

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ClickInit.Thiscompletestheinitialization.

SetConvergenceCriteria

FLUENTreportsaresidualforeachgoverningequationbeingsolved.Theresidualisameasureofhowwellthecurrentsolutionsatisfiesthediscreteformofeachgoverningequation.We'

lliteratethesolutionuntiltheresidualforeachequationfallsbelow1e-6.

Monitors>

Residual...

ChangetheresidualunderConvergenceCriterionforcontinuity,x-velocity,andy-velocity,allto1e-6.

Also,underOptions,selectPlot.Thiswillplottheresidualsinthegraphicswindowastheyarecalculated.

Thiscompletestheproblemspecification.Saveyourwork:

File>

Write>

Case...

Typeinpipe.casforCaseFile.ClickOK.Checkthatthefilehasbeencreatedinyourworkingdirectory.IfyouexitFLUENTnow,youcanretrieveallyourworkatanytimebyreadinginthiscasefile.

IterateUntilConvergence

Startthecalculationbyrunning100iterations:

Iterate...

IntheIterateWindowthatcomesup,changetheNumberofIterationsto100.ClickIterate.

Theresidualsforeachiterationisprintedoutaswellasplottedinthegraphicswindowastheyarecalculated.

（Clickpictureforlargerimage）

Theresidualsfallbelowthespecifiedconvergencecriterionof1e-6in46iterations.

Savethesolutiontoadatafile:

Data...

Enterpipe.datforDataFileandclickOK.Checkthatthefilehasbeencreatedinyourworkingdirectory.Youcanretrievethecurrentsolutionfromthisdatafileatanytime.

GotoStep6:

AnalyzeResults

Step6:

AnalyzeResults

CenterlineVelocity

We'

llplotthevariationoftheaxialvelocityalongthecenterline.

Plot>

XYPlot...

MakesurethatPositiononXAxisissetunderOptions,andXissetto1andYto0underPlotDirection.ThistellsFLUENTtoplotthex-coordinatevalueontheabscissaofthegraph.

UnderYAxisFunction,pickVelocity...andthenintheboxunderthat,pickAxialVelocity.

PleasenotethatXAxisFunctionandYAxisFunctiondescribethexandyaxesofthegraph,whichshouldnotbeconfusedwiththexandydirectionsofthepipe.

Finally,selectcenterlineunderSurfacessinceweareplottingtheaxialvelocityalongthecenterline.Thisfinishessettinguptheplottingparameters.

ClickPlot.

Thisbringsupaplotoftheaxialvelocityasafunctionofthedistancealongthecenterlineofthepipe.

Inthegraphthatcomesup,wecanseethatthevelocityreachesaconstantvaluebeyondacertaindistancefromtheinlet.Thisisthefully-developedflowregion.

Changetheaxesextents:

IntheSolutionXYPlotmenu,clickonAxes....UnderOptions,deselectAutoRange.TheboxesunderRangeshouldnowbeactivated.SelectXunderAxis.Enter1forMinimumand3forMaximumunderRange.

llturnonthegridlinestohelpestimatewheretheflowbecomesfullydeveloped.ChecktheboxesnexttoMajorRulesandMinorRulesunderOptions.ClickApply.

Now,pickYunderAxisandonceagaindeselectAutoRangeunderOptions,thenenter1.8forMinimumand2.0forMaximumunderRange.AlsoselectMajorRulesandMinorRulestoturnonthegridlinesintheYdirection.Wehavenowfinishedspecifyingtherangeforeachaxes,soclickApplyandthenClose.

GobacktotheSolutionXYPlotmenuandclickPlottoreplotthegraphwiththenewaxesextents.Wecanseethatthefully-developedregionstartsataroundx=3mandthecenterlinevelocityinthisregionis1.93m/s.

SavingthePlot

Savethedatafromthisplot:

IntheSolutionXYPlotWindow,checktheWritetoFileboxunderOptions.ThePlotbuttonshouldhavechangedtoWrite....ClickonWrite....Entervel.xyastheXYFileNameandclickOK.CheckthatthisfilehasbeencreatedinyourFLUENTworkingdirectory.

Now,saveapictureoftheplot:

LeavetheSolutionXYPlotWindowandtheGraphicsWindowopenandclickon:

File>

Hardcopy...

UnderFormat,chooseoneofthefollowingthreeoptions:

EPS-ifyouhaveapostscriptviewer,thisisthebestchoice.EPSallowsyoutosavethefileinvectormode,whichwillofferthebestviewableimagequality.AfterselectingEPS,chooseVectorfromunderFileType.

TIFF-thiswillofferahighresolutionimageofyourgraph.However,theimagefilegeneratedwillberatherlarge,sothisisnotrecommendedifyoudonothavealotofroomonyourstoragedevice.

JPG-thisissmallinsizeandviewablefromallbrowsers.However,thequalityoftheimageisnotparticularlygood.

Afterselectingyourdesiredimageformatandassociatedoptions,clickonSave...

Entervel.eps,vel.tif,orvel.jpgdependingonyourformatchoiceandclickOK.

Verifythattheimagefilehasbeencreatedinyourworkingdirectory.Youcannowcopythisfileontoadiskorprintitoutforyourrecords.

CoefficientofSkinFriction

FLUENTprovidesalargeamountofusefulinformationintheonlinehelpthatcomeswiththesoftware.Let'

sprobetheonlinehelpforinformationoncalculatingthecoefficientofskinfriction.

Help>

User'

sGuideIndex...

ClickonSinthelinksontopandscrolldowntoskinfrictioncoefficient.Clickonthesecond965link（normally,youwouldhavetogothrougheachofthelinksuntilyoufindwhatyouarelookingfor）.Wecanseeanexcerptontheskincoefficientaswellastheequationforcalculatingit.

ClickonthelinkforReferenceValuespanel,whichtellsushowtosetthereferencevaluesusedincalculatingtheskincoefficient.

Setthereferencevalues:

Report>

ReferenceValues...

SelectinletunderComputeFromtotellFLUENTtocalculatethereferencevaluesfromthevaluesatinlet.Checkthatdensityis1kg/m3andvelocityis1m/s.（Alternately,youcouldhavejusttypedintheappropriatevalues）.ClickOK.

GobacktotheSolutionXYPlotmenu.UncheckWritetoFileunderOptionssincewewanttoplottothewindowrightnow.WecanleavetheotherOptionsandPlotDirectionasissincewearestillplottingagainstthexdistancealongthepipe.

UndertheYAxisFunction,pickWallFluxes...,andthenSkinFrictionCoefficientintheboxunderthat.

UnderSurfaces,selectwallandunselectcenterlinebyclickingonthem.

Resetaxesranges:

GotoAxes...andre-selectAuto-RangefortheYaxis.SettherangeoftheXaxisfrom1to8byselectingXunderAxis,entering1underMinimum,and8underMaximumintheRangebox（remembertode-selectAuto-Rangefirstifitischecked）.

ClickApply,Close,andthenPlotintheSolutionXYPlotWindow.

Wecanseethatthefullydevelopedregionisreachedataroundx=3.0mandtheskinfrictioncoefficientinthisregionisaround1.54.Comparethenumericalvalueof1.54withthetheoretical,fully-developedvalueof0.16.

PickWritetoFileunderOptionsandclickWrite....Entercf.xyforXYFileandclickOK.

VelocityProfile

llnextplotthevelocityattheoutletasafunctionofthedistancefromthecenterofthepipe.Todothis,wehavetosettheyaxisofthegraphtobetheyaxisofthepipe（theradialdirection）.

Toplotthepositionvariableontheyaxisofthegraph,uncheckPositiononXAxisunderOptionsandchoosePositiononYAxisinstead.Tomakethepositionvariabletheradialdistancefromthecenterline,underPlotDirection,changeXto0andYto1.Toplottheaxialvelocityonthexaxisofthegraph,forXAxisFunction,pickVelocity...andAxialVelocityunderthat.

Sincewewanttoplotthisattheoutletboundary,pickoutletunderSurfaces.

ChangeboththexandyaxestoAuto-Range.

UncheckWritetoFileunderOptionssothatwecanseethegraph.ClickPlot.

Doesthislooklikeaparabolicprofile?

PickWritetoFileunderOptionsandclickWrite....Enterprofile.xyforXYFileandclickOK.

Toseehowthevelocityprofilechangesinthedevelopingregion,letusaddtheprofilesatx=0.6m（x/D=3）andx=0.12m（x/D=6）totheaboveplot.First,createalineatx=0.6musingtheLine/Raketool:

Surface>

Line/Rake

llcreateastraightlinefrom（x0,y0）=（0.6,0）to（x1,y1）=（0.6,0.1）.SelectLineToolunderOptions.Enterx0=0.6,y0=0,x1=0.6,y1=0.1.Enterline1underNewSurfaceName.ClickCreate.

Toseethelinejustcreated,select

Display>

Grid...

Notethatline1appearsinthelistofsurfaces.Selectallsurfacesexceptdefault-interior.ClickDisplay.Thisdisplaysallsurfacesbutnotthemeshcells.Zoomintotheregionneartheinlettoseethelinecreatedatx=0.6m.（Clickheretoreviewthezoomfunctionalitydiscussioninstep4.）line1isthewhiteverticallinetotherightinthefigurebelow.

Similarly,createaverticallinecalledline2atx=1.2;

（x0,y0）=（1.2,0）to（x1,y1）=（1.2,0.1）inthiscase.Displayitinthegraphicswindowtocheckthatithasbeencreatedcorrectly.

Nowwecanplotthevelocityprofilesatx=0.6m（x/D=3）andx=0.12m（x/D=6）alongwiththeoutletprofile.IntheSolutionXYplotmenu,usethesamesettingsasabove.UnderSurfaces,inadditiontooutlet,selectline1andline2.SelectNodeValuesund