简介：所有液体动态方程在他们的当模特儿的规模下面是有效的，意味着免费路径例如粒子并且意味着Boltzmann方程的碰撞时间规模和NavierStokes(NS)方程的水动力学规模。当前的计算液体动力学(CFD)集中于部分微分方程(PDE)的数字答案，并且它的目的是得到这些管理方程的精确答案。在如此的一个CFD惯例下面，它是难的开发盖住流动物理从的一个统一计划对水动力学运动因为没有能用Boltzmann做光滑的转变到当模特儿的NS的如此的管理方程，连续地可伸缩。液体动力学的学习需要超出传统的数字部分微分方程。出现设计应用程序，例如为近空间的飞行和流动和热转移在的空气车辆设计微设备，确实要求煤气的动力学的概念的进一步的扩大到物理现实，而非传统的可区分的管理方程的更大的域。在当前的阶段，非平衡流动物理很好还没由于适当工具的缺乏被探索了或清楚地理解。不幸地在当前的数字PDE途径下面，它是难的由于有效PDE的缺席开发如此的一个有意义的工具。以便多尺度的构造和类似于构造管理方程的Boltzmann或NS的当模特儿的过程的multiphysics模拟方法，一个数字算法的发展应该基于物理建模的第一个原则。在这份报纸，而不是跟随传统的数字PDE路径，我们介绍为CFD算法开发的作为一个原则的直接建模。因为所有计算与有限房间分辨率在一个discretized空格被进行，要当模特儿的流动物理不得不在网孔尺寸和时间步骤规模被做。这里，CFD是差不多分离数字进化方程的直接构造，在网孔尺寸和时间步骤将玩的地方，在建模的动态角色处理。与在网孔之间的比率的变化，尺寸和本地粒子意味着免费路径，从到水动力学波浪繁殖的运动粒子运输和碰撞的计划愿望俘获流动物理。基于直接建模，流动运动的连续动力学�

简介：Thetransitiontoturbulenceinflowswherethelaminarprofileislinearlystablerequiresperturbationsoffiniteamplitude."Optimal"perturbationsaredistinguishedasextremaofcertainfunctionals,anddifferentfunctionalsgivedifferentoptima.Weherediscussthephasespacestructureofa2Dsimplifiedmodelofthetransitiontoturbulenceanddiscussoptimalperturbationswithrespecttothreecriteria:energyoftheinitialcondition,energydissipationoftheinitialcondition,andamplitudeofnoiseinastochastictransition.Wefindthatthestatestriggeringthetransitionaredifferentinthethreecases,butshowthesamescalingwithReynoldsnumber.

简介：Theresultsfromsomegeneralcirculationmodelsshowdistinctradiativeforcing(RF)bydustaerosol,whichpotentiallyhasaneffectonclimatechange.ThedirectRFandregionalclimaticeffectsofdustaerosolovertheEastAsianregionareinvestigatedinthisstudyusingNCAR'sCommunityAtmosphericModelversion3.1.ThenegativeRFatthetopoftheatmosphere(TOA)andthesurface(SRF)hasbeenrevealedexceptforsomehigh-albedoregions,whichleadstoadecreaseinthesurfaceairtemperatureandbringsanincreaseofatmosphericradiativeheatingunderbothclear-andall-skyconditions.ThedecreaseinthesurfaceairtemperaturecanbefoundoverawideregionthatincludestheIndianpeninsulaandnorthwestChina.ItaccompaniesanincreaseineasternChinaandtheKoreanpeninsula,andtemperaturechangesarenotlimitedtoregionswithalargedustopticaldepth.AbeltofvaporincreaseisrevealedfromtheIndianpeninsulaextendingeasttonorthernChina,whilevaporcontentevidentlydeceasesinsouthwestChina.Anincreaseinprecipitationcanalsobefoundinthebeltofincreasedvaporaccompanyingthereductionofprecipitationacrosstheregionstothesouthof30oN.ThepatternofrainfallchangehelpstooffsetthetrendofincreasingwetnessinthesouthandincreasingdrynessinthenorthofChinainrecentyears.

简介：AnewapproachtoproducesuperfineWC-Copowderbydirectreductionandcarbonizationisproposed.Water-solublesaltscontainingWandCowereusedasrawmaterials.Tungstenandcobaltoxidepowder(CoWO4/WO3)wasfirstformedbyaspray-pyrolysistechnique,whichwasthenmixedwithcarbonblackandconvertedtoWC-Cocompositepowderat950℃for4hinN2atmosphere.Theresultingpowderhasaparticlesizeof100-300nm.

简介：Tortuosityisoneofthekeyparameterstocharacterizethetransportpropertiesofporousmedia.Therearemanymodelsfortortuosityestimationbasedonsomedefinitions:geometric,hydraulic,electric,anddiffusivedefinitions.However,relationshipsamongthosetortuositiesremainunclearduetothelackofdirectcomparisononthesameporousmedia.HerewefocusonhydraulicandelectrictortuositiesandhaveconductedaseriesoffiniteelementsimulationswiththeNavier–Stokesequationandtheequationforelectriccurrenttodirectlycomparetortuosities.Theresultsrevealedthat:(1)onaverage,hydraulictortuosityis15%greaterthanthatoftheelectricone;(2)theproposedmodelbasedonthevanGenuchten-typefunctionsuccessfullyapproximatesbothhydraulicandelectrictortuosities;(3)tortuositiesobtainedfromtheporousmediapackedwithcircularparticlesandsquareparticlesshowquantitativelysimilartrends.

简介：AnumericalschemeisdevelopedtoextendthescopeofthespectralmethodwithoutsolvingthecovariantandcontravariantformsoftheNavier-Stokesequationsinthecurvilinearcoordinates.TheprimitivevariablesarerepresentedbytheFourierseriesandtheChebyshevpolynomialsinthecomputationalspace.Thetimeadvancementisaccomplishedbyahigh-ordertime-splittingmethod,andacorrespondinghigh-orderpressureconditionatthewallisintroducedtoreducethesplittingerror.Comparedwiththepreviouspseudo-spectralscheme,inwhichtheNavier-Stokesequationsaresolvedinthecovariantandcontravariantforms,thepresentschemereducesthecomputationalcostand,atthesametime,keepsthespectralaccuracy.Theschemeistestedinthesimulationsoftheturbulentflowinachannelwithastaticstreamwisewavywallandtheturbulentflowoveraflexiblewallundergoingthestreamwisetravelingwavemotion.Theturbulentflowoveranoscillatingdimpleisstudiedwiththepresentnumericalscheme,andtheperiodicgenerationofthevorticalstructuresisanalyzed.

简介：Thispaperproceedsfromthegeneralcaseoftheunsymmetriclinearizedmulti-degreesoffree-dom(MDOF)systems.Byadoptingthegeneralcomplexmodaltheoryofthestatespace,theresponseanalysisforasys-temsubjectedtorandomexcitationofthesamesourceiscarriedoutusingasakindofdirectspectrumanalysismethodinfrequencydomain.Withtheinputofpowerspectraldensityfunctiongiven,theexplicitexpressionofthepowerspectraldensityfunctionmatrixoftheoutputresponsecanbeobtained.BytakingFourierinversetransform,theintegratedexpres-sionsofthecorrelationfunctionmatrixandofthespectrummomentmatrixareobtained.Comparingwiththetimedomainmethod,thismethodenjoysthemeritofvisualizationandavoidstheprocedureoftransformationfromtheobtainedre-sponsecorrelationfunctiontobesolvedfortheoutputspectrumutilizingFouriertransform.Thispaperhasextendedtheapplicationrangeofthetraditionalfrequencydomainanalysismethod.Themeansquarevaluesandvarietyofstatisticalval-uescanbeobtainedconveniently.Thismethodandthetimedomainmethodaredifferentinapproachbutequallysatisfac-toryintheirresults.

简介：在这份报纸，一条直接概率的途径(DPA)被介绍为能是任何一个的环境负担激动的非线性的系统提出并且解决时刻方程一静止或nonstationary随机过程。建议方法有的优点从起始的条件和相应外部刺激的统计特征直接获得回答时刻。首先，回答时刻方程直接基于DPA被导出，它完全独立于它?后来，关于关联的特定的假设都不刺激组织的/filtering途径被做。由在Gaussian闭合下面解决他们，回答时刻能被获得。随后，为时刻方程的数字答案的一个多尺度的算法被利用改进计算效率并且避免许多墙钟时间。最后，有蒙特卡罗(MC)模拟的结果的比较给好同意。而且，多尺度的算法的优点被一个设计例子也以效率表明。

简介：Bunchingofelementarystepsbysolutionflowisstillnotyetclarifiedforproteincrystals.Hence,inthisstudy,weobservedelementarystepsoncrystalsurfacesofmodelproteinhenegg-whitelysozyme(HEWL)underforcedflowconditions,byouradvancedopticalmicroscopy.WefoundthatinthecaseofaHEWLsolutionof99.99%purity,forcedflowchangedbunchedstepsintoelementaryones(debunching)ontetragonalHEWLcrystals.Incontrast,inthecaseofaHEWLsolutionof98.5%purity,forcedflowsignificantlyinducedbunchingofelementarysteps.TheseresultsindicatethatinthecaseofHEWLcrystals,themasstransferofimpuritiesismoresignificantlyenhancedbyforcedsolutionflowthanthatofsoluteHEWLmolecules.Wealsoshowedthatforcedflowinducedtheincorporationofmicrocrystalsintoamothercrystalandthesubsequentformationofscrewdislocationsandspiralgrowthhillocks.

简介：Calciumsulfatehemihydrate（CSH）whiskersweresynthesizedbyphasetransitioninCaCl2solutionunderatmosphericpressure.Analytical-gradecalciumsulfatedihydrate（ARCSD）wasusedastherawmaterialforthesynthesisofCSHwhiskers,accordingtoorthogonalexperiments.Theeffectsofreactiontemperature,ARCSDcontent,H2SO4content,andreactiontimewereinvestigated,andthecrystallizationconditionswereoptimized.Theas-preparedCSHwhiskersdisplayedaregularmorphologyandahighlyuniformsize,withanaspectratioof105.AsimulationsystemwasalsoestablishedbyblendingvarioussulfateswithARCSD,toevaluatetheeffectsofimpuritiesinfluegasdesulfurization（FGD）gypsum.ThemainaimwastoprepareCSHwhiskersdirectlyfromFGDgypsum,withoutanypurification,usingtheoptimizedconditions.Thisisafacilepotentialalternativeprocessforlarge-scaleproductionofCSHwhiskersusingabundantFGDgypsumassourcematerials.

简介：Inthispaper,wecombinethedirect-forcingfictitiousdomain(DF/FD)methodandthesharpinterfacemethodtoresolvetheproblemofparticledielectrophoresisintwodimensions.TheflowfieldandthemotionofparticlesaresolvedwiththeDF/FDmethod,theelectricfieldissolvedwiththesharpinterfacemethod,andtheelectrostaticforceontheparticlesiscomputedusingtheMaxwellstresstensormethod.Theproposedmethodisvalidatedviathreeproblems:effectiveconductivityofparticlecompositebetweentwoplanarplates,celltrappinginachannel,andmotionofparticlesduetobothconventionalandtravelingwavedielectrophoreticforces.

简介：微粒和集合使液化系统的充分解决的模拟与所谓的联合格子Boltzmann方法和时间驱动的难范围的模型(LBMTDHS)成功地被执行。在这个方法，分离粒子阶段被时间驱动的难范围的模型描述，并且连续液体阶段的管理方程与格子Boltzmann方法被解决。联合的Particlefluid被移动边界方法沉浸实现。时间平均模仿的结果的流动结构在轴的方向显示出核心体环结构的形成和voidage的S字形的分发，它是在使液化系统的典型现象。联合模拟，为推迟的精力消费Nst和搬运固体的结果从使液化的直接数字的模拟(DNS)是计算的，并且稳定性标准Nst/NT=min在扩展内存管理程序/水泡建议模型数字地被验证。而且，数字结果证明在微粒使液化的Nst/NT的价值在集合使液化比那高得多，但是Nst/NT=min为微粒和集合使液化是有效的。

简介：ThisletterreportsinletflowdisturbanceeffectsondirectnumericalsimulationofincompressibleroundjetatReynoldsnumber2500.Thesimulationemploysanaccurateprojectionmethodinwhichasixthorderbiasedupwinddifferenceschemeisusedforspatialdiscretizationofnonlinearconvectiveterms,withafourthordercentraldifferenceschemeusedinthediscretizationofthedivergenceofintermediatevelocity.Carefullyidentifyingrevealsthattheinletflowdisturbancehassomeinfluencesonthedistributionpatternofmeanfactorofswirlingstrengthintermittency.Withtheincreaseofinletdisturbancemagnitudejetcoreconeslightlyshortens,observabledifferencesoccurinthecenterlinevelocityanditsfluctuations,despitethenegligibleimpactsontheleastsquarefittedcenterlinevelocitydecayconstant(Bu)anddistributionparameter(Ku)forvelocityprofileinself-similarregion.

简介：Dynamicfluid-solidinteractionsarewidelyfoundinchemicalengineering,suchasinparticle-ladenflows,whichusuallycontaincomplexmovingboundaries.Theimmersedboundarymethod(IBM)isaconvenientapproachtohandlefluid-solidinteractionswithcomplexgeometries.Inthiswork,Uhlmann’sdirect-forcingIBMisimprovedandimplementedonasupercomputerwithCPU-GPUhybridarchitecture.Thedirect-forcingIBMismodifiedasfollows:thePoisson’sequationforpressureissolvedbeforeevaluationofthebodyforce,andtheforceisonlydistributedtotheCartesiangridsinsidetheimmersedboundary.Amultidirectforcingschemeisusedtoevaluatethebodyforce.Thesemodificationsresultinadivergence-freeflowfieldinthefluiddomainandtheno-slipboundaryconditionattheimmersedboundarysimultaneously.Thismethodisimplementedinanexplicitfinite-differencefractional-stepscheme,andvalidatedby2Dsimulationsoflid-drivencavityflow,Couetteflowbetweentwoconcentriccylindersandflowoveracircularcylinder.Finally,themethodisusedtosimulatethesedimentationoftwocircularparticlesinachannel.Theresultsagreeverywellwithpreviousexperimentalandnumericaldata,andaremoreaccuratethantheconventionaldirect-forcingmethod,especiallyinthevicinityofamovingboundary.

简介：Directsimulationof3-DMHD(magnetohydrodynamics)flowsinliquidmetalfusionblanketwithflowchannelinsert(FCI)hasbeenconducted.Twokindsofpressureequilibriumslot(PES)inFCI,whichareusedtobalancethepressuredifferencebetweentheinsideandoutsideofFCI,areconsideredwithaslotinHartmannwalloraslotinsidewall,respectively.ThevelocityandpressuredistributionofFCImadeofSiC/SiC_farenumericallystudiedtoillustratethe3-DMHDfloweffects,whichclearlyshowthatt...

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简介：Acouplednumericalmethodforthedirectnumericalsimulationofparticle-fluidsystemsisformulatedandimplemented,resolvinganorderofmagnitudesmallerthanparticlesize.Theparticlemotionisdescribedbythetime-drivenhard-spheremodel,whilethehydrodynamicequationsgoverningfluidflowaresolvedbythelatticeBoltzmannmethod(LBM).Particle-fluidcouplingisrealizedbyanimmersedboundarymethod(IBM),whichconsiderstheeffectofboundaryonsurroundingfluidasarestoringforceaddedtothegoverningequationsofthefluid.Theproposedschemeisvalidatedintheclassicalflow-around-cylindersimulations,andpreliminaryapplicationofthisschemetofluidizationisreported,demonstratingittobeapromisingcomputationalstrategyforbetterunderstandingcomplexbehaviorinparticle-fluidsystems.