Statisticsofvelocityandpreferentialaccumulationofmicro-particlesinboundarylayerturbulenceOriginalResearchArticle

Thedistributionofinertialparticlesinturbulentflowsisstronglynon-homogeneousandisdrivenbythestructureoftheunderlyingcarrierflowfield.Inthiswork,weuseDNScombinedwithLagrangianparticletrackingtocharacterizetheeffectofinertiaonparticlepreferentialaccumulation.WecomparetheEulerianstatisticscomputedforfluidandparticlesofdifferentsize,andobservedifferencesintermsofdistributionpatternsanddepositionrateswhichdependonparticleinertia.Specifically,differentstatisticsarerelatedtotheselectiveinteractionoccurringbetweenparticlesandcoherentflowstructures.Thisselectiveresponsecausesapreferentialsamplingoftheflowfieldbytheparticlesandeventuallyleadstothewell-knownphenomenonoflong-termparticleaccumulationintheboundarylayer.WetrytomeasureparticlepreferentialaccumulationwithaLagrangianparameterrelatedtotherateofdeformationofanelementalvolumeoftheparticlephasealongaparticletrajectory.IntheframeoftheLagrangianapproach,thisparameterismathematicallydefinedastheparticlepositionJacobian,image,computedalongaparticlepath.Thisquantityisrelatedtothelocalcompressibility/divergenceoftheparticlevelocityfield.Lagrangianstatisticsofimageshowthatcompressibilityincreasesforincreasingparticleresponsetimesimage(uptoimageandwithinthetimespancoveredbythesimulation).