swirl flow—fluent常见问题

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1、TheSingleReferenceFrame(MRF)ModelSolutionStrategiesforaRotatingReferenceFrame:(Segregatedsolveronly)ConsiderswitchingtheframeinwhichvelocitiesaresolvedbychangingthevelocityformulationsettingintheSolverpanel.(SeeSection10.2.5:ChoosingtheRelativeorAbsoluteVelocityFormula

2、tionfordetails.)(Segregatedsolveronly)UsethePRESTO!scheme,whichiswell-suitedforthesteeppressuregradientsinvolvedinrotatingflows.Ensurethatthemeshissufficientlyrefinedtoresolvelargegradientsinpressureandswirlvelocity.(Segregatedsolveronly)Reducetheunder-relaxationfact

3、orsforthevelocities,perhapsto0.3{0.5orlower,ifnecessary.Beginthecalculationsusingalowrotationalspeed,increasingtherotationalspeedgraduallyinordertoreachthefinaldesiredoperatingcondition(seebelow).TheMultipleReferenceFrame(MRF)Model(isrecommendedforsteadystate)limits:U

4、seoftherealizablek-emodelwithmultiplereferenceframesisnotrecommended.Strictlyspeaking,theuseofmultiplereferenceframesismeaningfulonlyforsteadyflow.However,FLUENTwillallowyoutosolveanunsteadyflowwhenmultiplereferenceframesarebeingused.Inthiscase,Youshouldcarefullyconsid

5、erwhetherthiswillyieldmeaningfulresultsforyourapplication.ParticletrajectoriesandpathlinesdrawnbyFLUENTusethevelocityrelativetothecellzonemotion.Formasslessparticles,theresultingpathlinesfollowthestreamlinesbasedonrelativevelocityandaremeaningful.Forparticleswithmass,h

6、owever,theparticletracksdisplayedaremeaningless.Similarly,coupleddiscretephasecalculationsaremeaningless.Analternativeapproachforparticletrackingandcoupleddiscrete-phasecalculationswithmultiplereferenceframesistotrackparticlesbasedonabsolutevelocityinsteadofrelativevelo

7、city.Tomakethischange,usethedefine/models/dpm/options/track-in-absolute-frametextcommand.Ifyouenablethetrack-in-absolute-frameoption,theinjectionvelocitiesarespecifiedrelativetotheabsoluteframe.Youcannotaccuratelymodelaxisymmetricswirlinthepresenceofmultiplereferencefr

8、amesusingtherelativevelocityformulation.Thisisbecausethecurrentimplementationdoesnotapplythetransformationused