简介：Aprogramincorporatingtheparallelcodeoflargeeddysimulation(LES)andparticletransportationmodelisdevelopedtosimulatethemotionofparticlesinanatmosphericturbulentboundarylayer(ATBL).Amodelofparticlesof100-micrometerordercouplingwithlargescaleATBLisproposed.Twotypicalcasesarestudied,onefocusesontheevolutionofparticleprofileintheATBLandthelandingdisplacementofparticles,whereastheotheronthemotionofparticlestream.

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简介：Heattransportisakeyenergeticprocessinmaterialsanddevices.Thereducedsamplesize,lowdimensionoftheproblemandtherichspectrumofmaterialimperfectionsintroducefruitfulphenomenaatnanoscale.Inthisreview,wesummarizerecentprogressesintheunderstandingofheattransportprocessinlow-dimensionalmaterials,withfocusontherolesofdefects,disorder,interfaces,andthequantummechanicaleffect.Newphysicsuncoveredfromcomputationalsimulations,experimentalstudies,andpredictablemodelswillbereviewed,followedbyaperspectiveonopenchallenges.

简介：在这研究，acoupled地区性的空气质量建模系统被使用调查时间在在空中的微粒事(PM10)的空间变化，在2004年4月17日的时期从Mentougou发源到北京市政的区域，并且在边界层之上的复杂地面和气象学的条件的影响组织并且PM10集中分布。有对观察数据的CALPUFF的表演的intercomparison被介绍并且考试散布阴谋被提供。统计证明在建模并且观察的数据之间的关联系数和性传播疾病分别地是0.86和0.03。模型结果的分析说明从Mentougou射出的污染物质能沿着某些运输小径被搬运到北京市政的区域，并且PM10集中分布显示出异质特征。到在北京市政的区域的PM10集中的Mentougou来源的贡献直到0.115g/m3。

简介：Thestudyofbed-loadtransportisofgreatsignificancebothintheoryandinpractice.Thispaperdiscussesthesaltationofbed-loadsolidgrainsinflowingwater.Experimentsandtheoreticanalysishavebeenmadebymeansofhigh-speedphotographingandadvanceddataprocessingtechniquewithacombinedmethodbasedonmechanicalandstatisticaltheories.Itindicatesthatthesaltationisthemainformofthebed-loadtransportunderordinaryflowingconditions.Inthemeantime,takingsuecessivesaltationasthemod-elofbed-loadtransport,systematicanalysishasbeenmadewithregardtothekinematicpropertiesandmechanismofsaltation.ThestatisticalanalysisshowsthattheprobabilitydensityfunctionsoftherelativeheightandlengthofsaltationareinconformitywithΓ-typedistribution,whiletheprobabilitydensityfunc-tionsoftherelativevelocitiesofsaltationareinconformitywiththeGaussiandistribution.

简介：Soilconsolidationwouldinducevariationsofitstransportcoefficientssuchashydraulicconductivityanddiffusioncoefficient.Thispaperpresentsastudyoftheinfluenceofbarrierconsolidationontransportcoefficients,anda3Dtransportmodelbasedonmixturetheoryisproposedfordescribingthelinersthatinvolvecirculardefectsinthegeomembrane.TheelastoplasticALPHAmodelisrevisedbyusingthespatiallymobilizedplane(SMP)criterionforsimulatingthedeformationofthesoils.Then,the3Dmodelcouplingthenonlinearconsolidationandcontaminantadvection-diffusionissolvedusingthefiniteelementsoftwareABAQUS.Theresultsshowthattheimportanceofreducingthedefectsizeinthegeomembraneandthelinerporositytocontrolthecontaminantconcentrationincrease.

简介：Liquidinjection,andfilmformationandtransportindense-phasegas-solidsfluidizedbedsarenumericallysimulatedinthreedimensionsusingacollisionalexchangemodelthatisbasedonthemechanismthatcollisionscausetransferofliquidmass,momentum,andenergybetweenparticles.Inthemodel,eachoftheparticlesisrepresentedbyasolidcoreandaliquidfilmsurroundingthecore.ThemodelisincorporatedintheframeworkofthecommercialcodeBarracuda?developedbyCPFDSoftware.ThecommercialsoftwareisanadvancedCFD-basedcomputationaltoolwheretheparticlesaretreatedasdiscreteentities,calculatedbytheMP-PICmethod,andtrackedusingtheLagrangianmethod.DetailsofthecollisionalliquidtransfermodelhavebeenpreviouslypresentedinO'Rourke,Zhao,andSnider(2009);thispaperpresentsnewcapabilitiesandproof-testingofthecollisionmodelandanewmethodtobetterquantifythepenetrationlength.Examplecalculationsofafluidizedbedwithoutliquidinjectionshowtheexpectedeffectofcollisionsonthereductionofgranulartemperature(fluctuationalkineticenergy)ofthebed.Whenappliedtoliquidinjectionintoadense-phasefluidizedbedunderdifferentconditions,themodelpredictsliquidpenetrationlengthscomparabletotheexperiments.Inaddition,thesimulationrevealsforthefirsttimethedynamicmixingoftheliquiddropletswiththebedparticlesandthetransientdistributionofthedropletsinsidethebed.

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简介：Thecatalystlayer(CL)ofprotonexchangemem-branefuelcell(PEMFC)involvesvariousparticlesandporesinmeso-scale,whichhasanimportanteffectonthemass,charge(protonandelectron)andheattransportcoupledwiththeelectrochemicalreactions.Thecoarse-grainedmoleculardynamics(CG-MD)methodisemployedasameso-scalestructurereconstructiontechniquetomimictheself-organizationphenomenainthefabricationstepsofaCL.Themeso-scalestructureobtainedattheequilibriumstateisfurtheranalyzedbymoleculardynamic(MD)softwaretoprovidethenecessarymicroscopicparametersforunderstandingofmulti-scaleand-physicsprocessesinCLs.Theprimaryporesizedistribution(PSD)andactiveplatinum(Pt)surfaceareasarealsocalculatedandthencomparedwiththeexperiments.Inaddition,wealsohighlighttheimplementationmethodtocombinemicroscopicelementarykineticreactionschemeswiththeCG-MDapproachestoprovideinsightintothereactionsinCLs.TheconceptsfromCGmodelingwithparticlehydrodynamics(SPH)andtheproblemsoncouplingofSPHwithfiniteelementmodeling(FEM)methodsarefurtheroutlinedanddiscussedtounderstandtheeffectsofthemeso-scaletransportphenomenainfuelcells.

简介：Thetransportandchemicalproductionprocessesofnitrate,sulfate,andammoniumaerosolsoverEastAsiawereinvestigatedbyuseoftheModels-3CommunityMulti-scaleAirQuality(CMAQ)modelingsystemcoupledwiththeRegionalAtmosphericModelingSystem(RAMS).Fortheevaluationofthemodel'sabilityindepictingtheir3-dimensionalconcentrationdistributionsandtemporalvariations,modeledconcentrationsofnitrate,sulfate,andammoniumaerosolsarecomparedwiththeobservationsobtainedatagroundstationinJapaninMarch2001andonboardofanaircraftDC-8on18and21March2001duringtheTransportandChemicalEvolutionoverthePacific(TRACE-P)fieldcampaign.Comparisonshowsthatsimulatedvaluesofnitrate,sulfate,andammoniumaerosolsaregenerallyingoodagreementwiththeirobserveddata,andthemodelcapturesmostimportantobservedfeatures,andreproducestemporalandspatialvariationsofnitrate,sulfate,andammoniumaerosolconcentrationsreasonablywell,e.g.,thetimingandlocationsoftheconcentrationspikesofnitrate,sulfate,andammoniumaerosolsarewellreproduced,butlargediscrepanciesbetweenobservedandsimulatedvaluesarealsoclearlyseenatsomepointsandsometimesduetothecoarsegridresolutionanduncertaintiesoftheemissionsusedinthisstudy.ThiscomparisonresultsindicatethatCMAQisabletosimulatethedistributionsofnitrate,sulfate,andammoniumaerosolsandtheirrelatedspeciesinthetroposphereoverEastAsiareasonablywell.

简介：Inthepresentstudy,computationalfluiddynamics(CFD)isusedtoinvestigateinspiratoryandexpiratoryairflowcharacteristicsinthehumanupperrespiratorytractforthepurposeofidentifyingtheprobablelocationsofparticledepositionandthewallinjury.Computedtomography(CT)scandatawasusedtoreconstructathreedimensionalrespiratorytractfromtracheatofirstgenerationbronchi.Tocompare,asimplifiedmodelofrespiratorytractbasedonWeibelwasalsousedinthestudy.Thesteadystateresultsareobtainedforanairflowrateof45L/min,correspondingtotheheavybreathingcondition.Thevelocitydistribution,wallshearstress,staticpressureandparticledepositionarecomparedforinspiratoryflowsinsimplifiedandrealisticmodelsandexpiratoryflowsinrealisticmodelonly.Theresultsshowthatthelocationofcartilaginousringsissusceptibletowallinjuryandlocalparticledeposition.