Fluent-UDF-14.5-L05-DPM

©2012ANSYS,Inc.June17,20131Release14.514.5ReleaseChapter5UDFsfortheDiscretePhaseModelUserDefinedFunctionsinANSYSFluent©2012ANSYS,Inc.June17,20132Release14.5TheLifeStoryofaDPMParticle•BIRTH:AnewparticleTracked_Particle*piscreatedbyaninjectionInjection*I–IthasaninitialmassP_MASS_INIT(p),aninitialvelocityP_VEL_INIT(p)[]andadiameterP_DIAM_INIT(p)andotherpropertiesrequiredfortheselectedDPMmodels.•TRANSPORT:Aparticleistransportedbytheflow.UDFscanalter:–DragcoefficientusingDEFINE_DPM_DRAG(name,Re,p)–BodyForcesusingDEFINE_DPM_BODY_FORCE(name,p,i)•PARTICLEMODIFICATION:Aparticle’spropertiescanbechangedusing:–aDEFINE_DPM_LAW(name,…)UDF–tochangeitspropertiessuchasP_MASS(p),P_DIAM(p)…•FLOWINTERACTION:Aparticlecaninteractwiththeflowusingsourceterms:–Mass,speciesandheattransferusesDEFINE_DPM_SOURCE(name,…)•DEATH:Particlescanbemadetodieortheyleavethedomainwith:–SpecialeffectsatwallsusingDEFINE_DPM_BC(name,…)–ReportdatawhenpassingthroughsurfacesusingDEFINE_DPM_OUTPUT(name,…)UDFs©2012ANSYS,Inc.June17,20133Release14.5DPMMacros(1)ThemostimportantdatatypeforDPMmodelisTracked_ParticleTracked_Particle*p;DPMtracksparticlesbyperforming“Lagrangian”trackingParticledataatthecurrentpositionisgotusingmacroslike:•P_DIAM(p)Particlediameter•P_VEL(p)[I]ParticleVelocity•P_T(p)ParticleTemperature•P_RHO(p)Particledensity•P_MASS(p)Particlemass•P_TIME(p)Currenttimeforparticle•P_DT(p)Particletimestep•P_LF(p)Particleliquidfraction•P_VFF(p)ParticlevolatilefractionManymoreparticledatamacrosareavailable©2012ANSYS,Inc.June17,20134Release14.5DPMMacros(2)Macrosforparticlepropertiesatentrytothecurrentcellhave“0”attheend:–P_DIAM0(p)Diameter–P_VEL0(p)[i]Velocity–P_T0(p)Temperature–P_RHO0(p)Density–P_MASS0(p)Mass–P_TIME0(p)Time–P_LF0(p)LiquidfractionMacrosfortheinitialparticlepropertiesatinjectionintothedomain:–P_INIT_DIAM(p)Diameter–P_INIT_MASS(p)Mass–P_INIT_RHO(p)Density–P_INIT_TEMP(p)Temperature–P_INIT_LF(p)LiquidfractionParticletimeatinjection=0.0©2012ANSYS,Inc.June17,20135Release14.5TheLifeStoryofaDPMParticle(Again)TRANSPORTAteachstagethroughacell,theparticle’sspeedandpositionareupdatedusingDEFINE_DPM_DRAGandDEFINE_DPM_BODY_FORCEUDFsBIRTHParticleentersthecellTRANSPORTPARTICLEMODIFICATIONParticleexitsthecellBIRTHAparticlecanhaveitsinitialpropertiessuchasP_INIT_MASS(p)changedinaDEFINE_DPM_INJECTION_INITUDFPARTICLEMODIFICATIONAteachstagethroughacell,theparticle’spropertiessuchasP_MASS(p)canbechangedUsingaDEFINE_DPM_LAWUDFFLOWINTERACTIONWhenaparticleleavesacell,thetotalchangesintheparticlecanbeusedtoaddsourcestotheflow.ThedifferenceinentryandexitpropertiessuchasP_MASS0(p)-P_MASS(p)canbeaddedtotheflowusingaDEFINE_DPM_SOURCEUDFFLOWINTERACTION©2012ANSYS,Inc.June17,20136Release14.5DPMMacros(3)–P_EVAP_SPECIES_INDEX(p)Evaporatingspeciesindexinmixture–P_DEVOL_SPECIES_INDEX(p)Devolatilizingspeciesindexinmixture–P_OXID_SPECIES_INDEX(p)Oxidizingspeciesindexinmixture–P_PROD_SPECIES_INDEX(p)Combustionproductspeciesindexinmixture–P_CURRENT_LAW(p)Currentlawindex–P_NEXT_LAW(p)Nextparticlelawindex©2012ANSYS,Inc.June17,20137Release14.5DPMMacros(4)MaterialPropertiesforparticles–P_MATERIAL(p)Materialpointerforparticles–DPM_SWELLING_COEFFI(p)Swellcoefficientfordevolatilization–DPM_EMISSIVITY(p)Particleradiationemissivity–DPM_SCATT_FACTOR(p)Particleradiationscatteringfactor–DPM_EVAPORATION_TEMPERATURE(p)Evaporationtemperature–DPM_BOILING_TEMPERATURE(p)Boilingtemperature–DPM_LATENT_HEAT(p)LatentHeat–DPM_HEAT_OF_PYROLYSIS(p)Heatofpyrolysis–DPM_HEAT_OF_REACTION(p)Heatofreaction–DPM_VOLATILE_FRACTION(p)Volatilefraction–DPM_CHAR_REACTION(p)Charfraction–DPM_SPECIFIC_HEAT(p,t)SpecificHeatattemperaturet©2012ANSYS,Inc.June17,20138Release14.5DPMFunctions•ThefollowinginteractionsonparticlescanbecustomizedbyUDFs:–Bodyforce-custombodyforcesontheparticles–Drag-userdefineddragcoefficientbetweenparticlesandfluid–SourceTerms-accessparticlesourceterms–Output-usercanmodifywhatiswrittenouttothesamplingplaneoutput–Erosion-calledwhenparticleencounters“reflecting”surface–DPMLaw-customlawsforparticles–ScalarUpdate-allowsuserstoupdateascalareverytimeaparticlepositionisupdated–Switch-changethecriteriaforswitchingbetweenlaws