01-EDEM-FLUENT

Revision2.1/1DEMSolutionsTraining:EDEM-CFDCouplingModuleforFLUENTIntroducestheEDEM-CFDCouplingModuleforFLUENT,howitworks,andsomeofthemodule’sfeaturesEDEM-CFDCouplingModuleforFLUENTPage2of151DEMSolutionsTraining:EDEM-CFDCouplingModuleforFLUENT2OverviewEDEMDEMsoftwareusedforintegratingparticle,fluid,andmachinedynamicsFLUENTConfigurablesingle-phaseandmulti-phasealgorithmsProvidesaframeworkforcoupledsoftwaredevelopmentEDEM-CFDCouplingModuleforFLUENTEDEMcouplestoFluentwithEulerianorLagrangiancouplingEDEMreplacesapproximationofsolidphaseinFluentwithexplicitcalculationofparticledynamicEDEM-CFDCouplingModuleforFLUENTPage3of1533EDEM-FluentProcessFlowDragforcesonparticlescalculatedusingdataextractedfromfluidmeshcellsDEMtimestep(s)startedatendoffluidsimulationtimestepForcesonfluidfromparticlesareintroducedintofluidthroughaseriesofmomentumsinksFluiditeratedtoconvergenceParticlepositionsupdatedCallsEDEMParticlepositionsinputintoFluent4SchemePanelEDEM-CFDCouplingModuleforFLUENTPage4of155CouplingMethodologies6Euler-LagrangianCouplingMethodEDEM’sLagrangianmethodsimilartoFluent’sDPM(DiscretePhaseModel)OnlymomentumisexchangedbetweenthetwophasesLagrangiancouplingmethodbestusedwhenthesolidfractionislow(lessthan10%)LagrangiancouplingfastertocalculaterelativetoEuleriancouplingEDEM-CFDCouplingModuleforFLUENTPage5of157Euler-EulerCouplingMethodEuleriancouplingmethodbetterthanLagrangianforflowswithahighersolidfractionEnergynottransferredduringcalculationofthecoupling;onlymassandmomentumneedtobeconservedEDEMpreventsparticlesfrommovingduringthefluidphaseandremovesallotherphasicinteractionParticleforcesandpositionsupdatedinDEMphase8MomentumExchangeMomentumisexchangedbetweensolidandfluidphasesforbothEulerianandLagrangiancouplingmethods:CFDiteratedtoconvergenceforatimestepEDEMtakescontrolofthesimulationandperformsoneorseveraliterations.EDEMparticlepositionsareupdatedduetocontactforces,gravityandadditionalforcesappliedbythefluidControlpassedbacktoFluent.AmomentumsinkisaddedtoeachofthemeshcellstorepresenttheeffectofenergytransferfromtheDEMparticlesEDEM-CFDCouplingModuleforFLUENTPage6of159VolumeFractionExchangeParticlevolumefractiontransferedtoFluentforEuleriancouplingonlyIdeallyEDEMparticlesaresmallerthanFluentmeshcellsAsingleparticleinEDEMcanbemadefrommultiplespheres.Thevolumeofamulti-sphereparticleispassedtoFluent(thedragmodelassumesaparticleisspherical)10RelaxationFactorsMomentumtransferandvolumefractiontransfercanbeunder-relaxedtoprovidegreaterstabilityontheCFDside:Pnew=xPcalculated+(1–x)PoldWherePisthemomentum,xistherelaxationfactorTypicallyrelaxationfactorsvaryfrom0.1(veryslowdensephasesimulations)to1.0(fastflowingdilutesimulations)EDEM-CFDCouplingModuleforFLUENTPage7of1511SamplePointsSamplepointsallowlargeparticlestotransfervolumefractiontomeshcellsupto2xsmallerthantheparticlesIncreasingthesamplepointsincreasestheaccuracyandstabilityofEuleriansimulationsAsamplepointof1isenoughwhereparticlesaremorethan60%smallerthanthemeshcellsSmallmeshcellsunlikelytocontainparticlevolumefluidcellsampleparticlemiiDEMVNVS∑==1α12TimestepsCFDtypicallyusesatimestepofordersof10–100greaterthanDEMPerformingasingleCFDtimestepforeveryDEMtimestepisinefficient,soaratioischosen:Mustbesmallenoughtoassumethefluidflowpatterndoesn’tchangesignificantlyduringtheDEMiterationEachparticleshouldbeinafluentmeshcellforaminimumofthreeiterationsRatiomustbesuchthattheCFDcansuccessfullyiteratetoconvergenceonreturnfromtheDEMSmallestpossibleedem:fluenttimestepratiois1:1EDEMandFluenttimestepssynchronizedautomaticallyEDEMtimedatastoredineachFluentcasefileEDEM-CFDCouplingModuleforFLUENTPage8of1513DragModels14DragModelsTheEDEM-CFDCouplingModuleforFLUENThasseveraldragmodeloptions:FreestreamDragModel–freestreamdragmodelmodifiedtocalculateforcesonparticlesErgunandWen&Yu–modifiedfreestreamdragDiFelice–addsporositycorrectiontermUser-Defined–writeanduseyourownplug-indragmodelsEDEM-CFDCouplingModuleforFLUENTPage9of1515DragCalculationBoundingsphereusedtocalculatethedragforcefornon-sphericalparticlesLimitedparticlesizesincefluiddataistakenfromthemeshcellcontainingthecenteroftheparticleThedragcoefficient,CD,isdependentontheReynoldsnumber,Re:Whereρisthefluiddensity,μistheviscosity,listhediameteroftheparticlesboundingsphere,andvistherelativevelocitybetweenthefluidandtheparticleBuoyancymustalsobetakenintoaccount:µρvl=ReVgFBρ−=16DragModelTheoryFreestreamDragModelFreesteamdragforasphereiscalculatedfrom:WhereAistheprojectedareaofthesphereErgunandWen&YuDragModelAccordingtotheworkofTwente:WhereVisthevolumeofthesphere,eisthevoidageoftheFluentcell,and:||5.0vvACFDρ=evVF−=1βEDEM-CFDCouplingModuleforFLUENTPage10of1517DragModelTheoryDiFeliceDragModelAddsporositycorrectiontermtothefreestreamdragmodeltotakeintoaccounttheeffectsondragofneighboringparticles.Calculatedfrom:Whereeisthevoidage/porosityandxisgivenby:18OtherModelsEDEM-CFDCouplingModuleforFLUENTPage11of1519LiftModelsTheEDEM-CFDCouplingModuleforFLUENThasseveralliftmodeloptions:SaffmanLift–liftduetovelocit