多相流模型经验谈

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1、多相流模型经验谈多相流的介绍：Currentlytherearetwoapproachesforthenumericalcalculationofmultiphaseflows:theEuler-LagrangeapproachandtheEuler-Eulerapproach.TheEuler-LagrangeApproach:TheLagrangiandiscretephasemodelinFLUENTfollowstheEuler-Lagrangeapproach,thisapproachisinappropriateforthemodelingofliquid-liquidmixtur

2、es,fluidizedbeds,oranyapplicationwherethevolumefractionofthesecondphaseisnotnegligible.TheEuler-EulerApproach:InFLUENT,threedifferentEuler-Eulermultiphasemodelsareavailable:thevolumeoffluid(VOF)model,themixturemodel,andtheEulerianmodel.1)TheVOFModel:itisdesignedfortwoormoreimmisciblefluidswherethepo

3、sitionoftheinterfacebetweenthefluidsisofinterest.ApplicationsoftheVOFmodelincludestratifiedflows,free-surfaceflows,filling,sloshing,themotionoflargebubblesinaliquid,themotionofliquidafteradambreak,thepredictionofjetbreakup(surfacetension),andthesteadyortransienttrackingofanyliquid-gasinterface.2)Mix

4、turemodel:Applicationsofthemixturemodelincludeparticle-ladenflowswithlowloading,bubblyflows,sedimentation,andcycloneseparators.Themixturemodelcanalsobeusedwithoutrelativevelocitiesforthedispersedphasestomodelhomogeneousmultiphaseflow.3)ApplicationsoftheEulerianmultiphasemodelincludebubblecolumns,ris

5、ers,particlesuspension,andfluidizedbeds.离散相模型（离散相的装载率10～12%）求解参数的设定：OptionsforInteractionwithContinuousPhase：Forsteady-statesimulations,increasingtheNumberofContinuousPhaseIterationsperDPMIterationwillincreasestabilitybutrequiremoreiterationstoconverge.UpdateDPMSourcesEveryFlowIterationisrecommended

6、whendoingunsteadysimulations;ateveryDPMIteration,theparticlesourcetermsarerecalculated.LengthScale:controlstheintegrationtimestepsizeusedtointegratetheequationsofmotionfortheparticle.AsmallervaluefortheLengthScaleincreasestheaccuracyofthetrajectoryandheat/masstransfercalculationsforthediscretephase.

7、LengthScalefactor:AlargervaluefortheStepLengthFactordecreasesthediscretephaseintegrationtimestep.颗粒积分方法：numerics叶中trackingscheme选项1）implicitusesanimplicitEulerintegrationofEquation23.2-1whichisuncondi