简介:混合象粉末那样的微粒是在包括药品的许多工业的一个重要过程,塑料,家庭产品(例如detergents)并且食物处理。产品的质量取决于他们接着取决于几何设计和操作条件的成分材料混合的度。由于在混合器几何学和小粒的材料之间的相互作用的理解的缺乏,不幸地,有限进步在优化混合器设计被取得了。分离元素方法(DEM)是允许粒子系统被模仿并且混合被预言的一种计算技术。模拟是在困难或昂贵用传统的试验性的途径获得的不同混合器的表演上获得信息的一个有效方法。这里,我们表明DEM怎么能被用来解开流动动力学并且评定在设备的几种不同类型混合。这些设备使用了混合或微粒的使成粒状,当控制的严肃,bladed和高度砍,广泛地被分类。我们也在混合表演和使用DEM测试弗鲁德数字可伸缩是否对预言旋转混合器的规模性能合适探索粒子形状的角色。
简介:Semi-periodicstructuresnamelyinclinedwavystructures(IWS)areexperimentallyobservedincompressiblemixinglayersattwoconvectiveMachnumbers(Mc=0.11and0.47).FlowstructuresarevisualizedbythelaserinducedplanarlaserMiescattering(PLMS)technique.TwomethodsaredevelopedtoinvestigatethespatialdistributionandgeometryofIWS:(1)thedominantmodeextraction(DME)method,toextractthedominantmodesofIWSfromthestreamwisegray-levelfluctuation,and(2)thephasetracking(PT)method,toidentifytheshapeofIWS.TheresultssuggestthatpressureperturbationsaccountfortheformationofIWSintheinitialmixingregionandthejointefectofdilatationandcoherentvorticesenhancesIWSinthewelldevelopedregion.Thelargetransverse(cross-flow)scaleoftheIWSandtheirrelationtocoherentvortices(CV)indicatethatthedisturbanceoriginatedfromCVinthemixingcenterpropagatesfarintothefreestreams.TheDMEandthePTmethodareshowntobetheefectivetoolstostudythegeometricalfeaturesofwavystructuresincompressibleshearflows.
简介:Theprocessingoffine-grainedparticleswithdiametersbetween1and10micronsisdifficultduetostrongvan-der-Waalsattractionforces.Inordertoimprovethehandlingproperties,thefine-grainedparticles,i.e.host-particles,arecoatedwithvariousnanoparticles,i.e.guest-particles.Themixingoffine-grainedpowdersisinfluencedbyparticle-particleinteractions.Iftheseforcesaredistinctivelyused,bothinteractiveandorderedmixtu.rescanbeproduced.Theseparticlemixturesconsistofcomposite-particlesthathavenewphysicalproperties.Thesemodifiedpropertiesdependstronglyonthecoatingprocess,thediameter-andmass-relationshipoftheguest-andthehost-particles.Thepropertiesofthecomposite-particlescansystematicallybeadjustedtotherequirementsofindustrialapplications.Forexample,alaboratorybubblingfluidizedbedcanbeusedtodescribetheconveyingbehaviorofthefunctionalizedhost-particles.Applicationsforthefunctionalizedparticlesareinthepharmaceuticalandthepowdercoatingindustries,e.g.enhanceddrypowderinhalersandthinlacquerfilms.Thepresentresearchcomparesthreedifferentmixing/coatingprocesses.Thecomposite-particlesarecharacterizedbyTEM,SEMandwiththeirfluidizationcharacteristics.Thecoatingprocessitselfismonitoredbytheelectrostaticchargeoftheparticles.
简介:不同液体的混乱混合生产旋绕的结构到分开这些液体的接口。为能溶合的液体(是这里考虑了),这个接口被定义为50%集体集中isosurface。为导致的冲击波(Richtmyer-Meshkov)不稳定性,我们发现接口当计算网孔被精制,逐渐地复杂。如果Kolmogorov规模相对网孔是小的,这界面的混乱被粘性,或由计算网孔割掉。在集成的接口统计的政体,我们然后检验混合,即集中统计,由质量调整了散开。为比统一显著地大的Schmidt数字,典型地代表液体或稠密的血浆,另外的网孔精炼通常被需要克服数字集体散开并且完成混合问题的一个集成的答案。然而,与前面追踪的利益并且与一个算法,那允许有限接口散开,我们能在Schmidt数字一致地保证集中。我们证明不同答案源于Schmidt数字的变化。我们建议潜水艇格子粘性和可能在现实主义的格子层次允许集成的答案的集体散开parameterizations。
简介:Transversemixingcharacteristicsofsoluteintheopenchannelflowcanprovideusefulinformationforriverenvironmentalmanagement.Thelateralmixingcoefficientisacrucialparameterforreproducingthetransversemixingeitherbynumericalsimulationorbyanalyticalprediction.Sincethesolutemixingcanbegreatlyaffectedbythelateralvariationsinwaterdepth,mixingcoefficientshouldbedeterminedineachsub-section(i.e.,themainchannel,sideslopeandfloodplain)separately.Inthisarticle,thetransversemixinginasymmetrictrapezoidalcompoundchannelwasstudiedbasedonlaboratorymeasurementoflongitudinalandtransversevelocitycomponentsandlateraldistributionofsoluteconcentration.ThelateralmixingcoefficientwasestimatedbyadoptingdifferentSchmidtnumbersindifferentsub-sectionsdividedaccordingtothedevelopingtrendoftheeddyviscosity,andfinallyapiecewiselinearprofileofmixingcoefficientwasadoptedtoanalyticallypredictthetransversesoluteconcentration.Thecomparisonbetweentheanalyticallypredicteddataandthemeasuringsoluteconcentrationprovedthatthisisaneffectivewaytoestimatethelateralmixingintheopenchannelflowwithlateralvariationsinwaterdepth.
简介:Stokesdriftisthemainsourceofverticalvorticityintheoceanmixedlayer.InthewaysofCoriolis-StokesforcingandLangmuircirculations,Stokesdriftcansubstantiallyaffectthewholemixedlayer.AmodifiedMellor-Yamada2.5levelturbulenceclosuremodelisusedtoparameterizeitseffectonupperoceanmixingconventionally.Resultsshowthatcomparingsurfaceheatingwithwavebreaking,Stokesdriftplaysthemostimportantroleintheentireoceanmixedlayer,especiallyinthesubsurfacelayer.Asexpected,Stokesdriftelevatesboththedissipationrateandtheturbulenceenergyintheupperoceanmixing.Also,influenceofthesurfaceheating,wavebreakingandwindspeedonStokesdriftisinvestigatedrespectively.ResearchshowsthatitissignificantandimportanttoassessingtheStokesdriftintooceanmixedlayerstudying.Thelaboratoryobservationsaresupportingnumericalexperimentsquantitatively.
简介:TheresultsofBryeonlargedeviationsforempiricalmeasuresofstationaryφ-mixingsequencesareextended.Bryestateshisresultsintheusualweaktopologyonthespaceofprobabilitymeasures.Inthispaper,undersomewhatweakerassumptionsthanthoseofBryc,theauthorextendsBrye'sresultsbytakingthefinertopologywhichisgeneratedbytheintegralsoverboundedmeasurablefunctions.
简介:1.IntroductionandMainResultSincethedefinitiononthecompleteconvergencewasintroducedbyHsuandRobbins[1],therehavebeenmanyauthorswhodevotethemselvestothestudyonthisconvergenceofiidrandomvariables,seeGut[2,3],BaiandSu[4]andLin[5].Meanwhile,somescholarshav...
简介:Thefar-fieldnoiseradiatedfrommixinglayersisdeterminedbythenear-fieldflowdynamicswhichissensitivetotheinitialperturbationofinstabilityintroducedphysicallyornumerically.Thisstudyfocusesontheeffectsofthephasedelayintwoinitialperturbations,oneatthefundamentalwavenumberandtheotheratitssubharmonicbothcalculatedfromlinearinstabilityanalysis,onthesoundgenerationinmixinglayers.Whendifferentphasedelaysφ_1changingfromzeroto2πisappliedonthefundamentalmode,weobservedifferentvortexmergingprocesses(e.g.vortexpairingortearing).Thestrongnonlinearinteractioninthemergingprocessgeneratesmostofthenoisefrommixinglayers.Thereshowsapatterninaperiodof2πfortheresponseoffar-fieldsoundtothechangeofφ_1.Similareffectsonthedynamicsandacousticscanbeachievedbyaddingdifferentphasedelaysφ_2tothesubharmonicmodeinstead,however,theresponserepeatsinaperiodofonlyπforφ_2.Theeffectsofthecombinationofdifferentphasedelaystootherparameters,includingtheamplitudeandwavenumberforeachperturbations,arealsoinvestigated.Alltheresultsindicateacriticalroleofnonlinearityinthesoundgenerationmechanismofmixinglayers.
简介:Inthisstudy,particleimagevelocimetrywasappliedtoinvestigateflowfieldsofwormlikemicelle(WLM)fluidsinamixingtankequippedwithafour-blade,down-pumping,pitchedbladeturbine.First,therheologyofWLMfluidswasinvestigated,andtheCarreaumodelwasutilizedtodescribetheirapparentviscosity.Then,theeffectsoftherotationspeedsandrheologicalpropertiesontheflowfieldswerestudiedusingdifferentWLMfluidsatdifferentrotationspeeds.TheresultsrevealedthatwithincreasingReynoldsnumber,thedischargeangledecreasesandthecarvensizeincreases.Furthermore,elasticeffectsofWLMfluidsleadtoamorecurvedflowandasmallercarven.
简介:Inabiasedphotorefractivecrystal,theprocessoftwoone-dimensionalwavesmixing,i.e.,thedynamicalevolutionofbothpumpbeamandsignalbeam,istracedbynumericallysolvingthecoupled-waveequation.Directsimulationsshowthatthepropagationandstabilityofthetwobeamsarecompletelydeterminedbythesystemparameters,suchastheexternalbiasfield,theintensityandthebeamwaistofthepumpbeam.Byadjustingtheseparameters,onecancontrolthestateoftwoGaussianwavesmixing.Thenumericalresultsarehelpfulforperformingatwo-wavemixingexperiment.
简介:Let{X,Xn;n≥1}beastrictlystationarysequenceofρ-mixingrandomvariableswithmeanzeroandfinitevariance,SetSn=∑^nk=1Xk,Mn=maxk≤n|Sk|,n≥1.Supposelimn→∞ES^2n/n=tα^2>0and^∞∑n=1ρ^2/d(2^n)<∞,whered=2,if-12(b+1),ifb≥0.Itisprovedthat,foranyb>-1,limε^2(b+1)ε→0^∞∑n=1(loglogn)^b/nlognP{Mn≥εσ√2nloglogn}=2/(b+1)√πГ(b+3/2)^∞∑k=0(-1)^k/(2k+1)^2b+2,whereГ(·)isaGammafunction.
简介:Thisstudypresentsthenumericalresultsforthethree-dimensionalnaturalgas-airmixinginarectangularsubsonicchannelunderthestandarddatumstate.ThelowerandupperdecompositionmethodwasemployedtoobtainthesolutionsofthefullNavier-Stokesequationscapableofdescribingcompressiblefluidmixing.Gridwasgeneratedbytheareaorthogonaltechnique.Theresultsindicatethatthree-dimensionalmixingbetweenNaturalGas(NG)andairhasmorecomplicatedcompressiblewavesaroundtheinjectionnozzle.Thepresenceofinjectionwithlargespeedcansuppresstheboundaryseparationhappenedoccurringatthetopwallduetothechannelexpansion,butmakesthenear-wakeflowmorecomplicated.Themixingregioncanbewidenedbyincreasingtheinjectionspeed.TherecurrenceofthevortexstructureandthecoherentstructurecanbefoundfromthefullNavier-Stokessimulation.ItcanbeconcludedthattheincreaseintheinjectionvelocitycanimprovetheeffectivenessofmixingofNGandairinthenearwakeoftheinjectors.
简介:Considera-mixingsequenceofidenticallydistributedrandomvariableswiththeunderlyingdistributioninthedomainofattractionofthenormaldistribution.Thispaperprovesthatlawoftheiteratedlogarithmholdsfor-mixingsequencesofrandomvariables.OurresultsgeneralizeandimproveTheorems1.2-1.3ofQiandCheng(1996)fromthei.i.d.caseto-mixingsequences.
简介:混合的Diapycnal(DM)在上面太平洋的600m从全球温度咸度侧面计划(GTSPP)基于观察的巨大的数量被估计,用finescaleparameterization的紧张版本。在每个季节的DM展出类似的分发模式,这被发现,但是在细节不同。DM的增强与底部粗糙有关,表面在惯性附近的精力,和最近到赤道。不平的地形学表演在东北太平洋在Mendocino破裂地区附近在侧面引起的加强的DM,和产生风的在惯性附近的精力引起的提高的DM出现在南部的海洋的西的区域。作为与以前的估计相比,在这个工作的DM估计有更好空间的范围和更好的分辨率,并且更重要地,它包含季节的可变性。而且,产生DM数据集是gridded,为为应用程序建模使它变为合适。