简介：Adirectnumericalsimulationisperformedon2563gridsfordecayingisotropicturbulence.Thetotalkinematicenergy,Taylormicro-scale,Taylormicro-scaleReynoldsnumberandthevelocityderivativeskewnessarecalculated.Thesnapshotsofenergyspectraandenergytransferspectraareplotted.ThesemeasurementsverifytheDIApredictions:decayingisotropicturbulencehastheenergypropagationandoccupiesthefinaldecayperiods.Theskewnessremainstosomelevelwithsmallvariationeveninthefinaldecayperiod.

简介：Inthispaper,thewaves’breakingintheleewavesissuccessfullysimulatedbytheatmosphericmesoscalenumericalmodelwithasecond-ordertur-bulentclosure.Itisfurtherprovedthattheturbulenceinthewave-breakingregionplaystheroleofintensemixingfortheaveragefield,whichleadstothetrappingofupwardpropagatingwavesandthuspromotesthedevelopmentofthedownslopewind.Theturbulentstructureinthewave-breakingregionisdiscussedandthefol-lowingconclusionsareobtained:(1)Inthewave-breakingregion,theturbulentheatfluxestransferfrominsidetooutsideandtheturbulentmomentumfluxestransferfromoutsidetoinside.(2)Inthewave-breakingregion,theturbulentenergymainlycomesfromthewindshearandthebuoyancypromotestheturbulentdevelopmentonlyinpartoftheregion.(3)Intheupperpartofthewave-breakingregion,theturbulentmomentumfluxesbehaveasacounter-gradienttransfer.(4)Theturbulentmixinginthewave-breakingregionisnon-local.

简介：在这份报纸，我们在作者组进行的可压缩的骚乱上考察一些最近的研究，它在为围住墙的骚乱开发抑制大旋涡模拟(CLES)上在可压缩的各向同性的骚乱(市民)和应用研究上包括基本研究。在第一部分，我们实质上以最新建议的混合compactweighted开始为被用来构造市民的一个系统的数据库的市民模拟的nonoscillatory(WENO)计划。用这个数据库，可压缩的骚乱的各种各样的基本性质被检验了，包括统计并且从一个Lagrangian观点的可压缩的模式，shockletturbulence相互作用，小规模上的本地压缩的可能性的效果，动能串联，和一些初步的结果可伸缩。在第二部分，CLES的想法和公式被考察，处于可压缩的工程问题由CLES和一些应用程序的确认列在后面。

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简介：ThispaperprovidesacomprehensiveintroductiontothemajorprogressintransitionandturbulencestudiesinChinaoverthepastthirtyyears.Despitetheauthor’sbestefforts,therearesomeunavoidableomissions.Weexpectthatwiththecontinueddeepeningofturbulenceresearch,Chinesescholarswillmakeincreasingcontributionsinthisfield,whichwillcertainlyhavestronginfluenceontheestablishmentofaChinaSchoolofTurbulence.

简介：Mostfluidflowsinnatureandengineeringapplicationsareinthestateofturbulence.Turbulentmotionsusuallyexhibitawiderangeofspatialandtemporalscales,suchastheflowofnaturalgasandoilinpipelines,thewakesofcarsandsubmarines,theboundarylayerofanaircraft,thecurrentintheoceansurface,theatmosphericboundarylayer,theinterstellargasclouds(gaseousstars),andtheEarth’swakeinthesolarwind.Turbulencecangreatlyimprovetheheatandmasstransferefficiencyofmacroscopicflow.Forexample,chemicalengineersuseturbulencetomixupandhomogenizefluidcomponentsandtoincreasechemicalreactionratesinliquidsorgases.However,turbulencecanalsoleadtoincreasesindrag,aerodynamicheat,andhydrodynamicandaerodynamicnoise.Forinstance,theaerodynamicloadingofhigh-speedaircraftcanbesignificantlyincreasedduetoturbulence.

简介：Thenumericalandphysicalissuesofsimulationsoncompressibleturbulencearereviewedinthepresentpaper.Anoutlineoftheglobalspectralmeth-odsandtheprogressofrecentlocalspectralmethodsareillustrated.Severaltypicalsubjectsinthisfieldarestudied,includinghomogeneousisotropicturbulence,au-toignitioninpremixedturbulence,interactionbetweenflamesandturbulence,andshockwaveinturbulence.Theresultsofthenumericalsimulationsarediscussed,enablingustodiscoverandtounderstandthephysicalphenomenawhichhavenotbeensolvedbyexperiments.

简介：Wefindanasymptoticexpressionforthecharacteristictimescalesofdecorrelationprocessesinweaklycompressibleandisothermalturbulence.ThisresultisusedintheEddy-DampedQuasi-NormalMarkovianequationtoderivethescalingsofcompressibleenergyspectra:(1)iftheacousticwavesaredominant,thecompressibleenergyspectraexhibit?7/3scaling;(2)iflocaleddystrainingisdominant,thecompressibleenergyspectraarescaledas?3.Meanwhile,theenergyspectraofincompressiblecomponentsdisplaythesamescalingof?5/3asthoseinincompressibleturbulence.Thedirectnumericalsimulationsofweaklycompressibleturbulenceareusedtoexaminethescaling.

简介：TheHongKongObservatory(HKO)provideslow-levelturbulencealertingservicefortheHongKongInternationalAirport(HKIA)throughthewindshearandturbulencewarningsystem(WTWS).IntheWTWS,turbulenceintensitiesalongtheflightpathsoftheairportareestimatedbaseduponcorrelationequationsestablishedbetweenthesurfaceanemometerdataandtheturbulencedatafromresearchaircraftbeforetheopeningoftheairport.Theresearchaircraftdataarenotavailableonday-to-daybasis.Theremotesensingmeteorologicalinstruments,suchastheDopplerlightdetectionandranging(LIDAR)andradar,maybeusedtoprovidedirectmeasurementsofturbulenceintensitiesovertherunwaycorridors.TheperformancesofLIDAR-andradar-basedturbulenceintensitydataarestudiedinthispaperbasedonactualturbulenceintensitymeasurementsmadeon423commercialjetsforatypicalcaseofterrain-inducedturbulenceinassociationwithatyphoon.Itturnsoutthat,withthetuningoftherelativeoperatingcharacteristic(ROC)curvebetweenhitrateandfalsealarmrate,theLIDAR-basedturbulenceintensitymeasurementperformsbetterthantheanemometer-basedestimationofWTWSforturbulenceintensityatmoderatelevelorabove.Ontheotherhand,theradar-basedmeasurementdoesnotperformaswellwhencomparedwithWTWS.BycombiningLIDAR-andradar-basedmeasurements,theperformanceisslightlybetterthanWTWS,mainlyasaresultofcontributionfromLIDAR-basedmeasurement.Asaresult,theLIDAR-basedturbulenceintensitymeasurementcouldbeusedtoreplaceanemometer-basedestimatefornon-rainyweatherconditions.Furtherenhancementsofradar-basedturbulenceintensitymeasurementinrainwouldbenecessary.

简介：到流入的骚乱发展的敏感狂暴的统计在microscale被调查城市的大气的环境流动。大旋涡的模拟(更少)被执行，在哪个流入误差被根据雷纳兹应力或精力系列转变一块充分发达的狂暴的地引进。理论分析被在狂暴的动能的预算方程忽视散开术语执行。结果显示出那，错误由雷纳兹压力腐烂引起了直到充分发达的水平的(i)被完成，并且(ii)典型长度规模引起的错误立即增加然后减少。当垂直坐标增加时，改变流入错误的率的streamwise变弱。内部层的流入和外部层的数据的效果的进一步的测试显示出那，流入内部层的数据统治近的域，和流入外部层的数据统治远域。

简介：Hydrodynamicinstabilityandthemechanismsforturbulenceonsetandself-sustainingaretworesearchquestionsthathavepuzzledthescientistsforoveracentury,yetrenewedinterestandsignificantprogressoccurredinthelastdecadeorso.WeknowonlyfewexactanalyticalsolutionsoftheNavier-Stokesequations,theequationsgoverningtheflowofsimplefluidslikewaterandair,andmostoftheseareneverobservedinapplicationsorlaboratory

简介：Experimentalandnumericalstudieshaveshownsimilaritiesbetweenlocalizedturbulenceinchannelandpipeflows.Byscalinganalysisofadisturbed-flowmodel,thispaperproposesalocalReynoldsnumberReMtocharacterizethethresholdoftransitiontriggeredbyfinite-amplitudedisturbances.TheReMrepresentsthemaximumcontributionofthebasicflowtothemomentumratiobetweenthenonlinearconvectionandtheviscousdiffusion.ThelowercriticalReMobservedinexperimentsofplanePoiseuilleflow...

简介：Theoreticalresultsonthescalingpropertiesofturbulentvelocityfieldsarereportedinthisletter.BasedontheKolmogorovequationandtypicalmodelsofthesecond-orderstatisticalmoments(energyspectrumandthesecond-orderstructurefunction),wehavestudiedtherelativescalingusingtheESSmethod.ItisfoundthattherelativeEESscalingexponentS_2isgreaterthantherealortheoreticalinertialrangescalingexponentξ_2,whichisattributedtoanevidentbumpintheESSrange.

简介：Arecentlyintroducednonlinearmodelundergoesevaluationsbasedontwoisotropicturbulentcases:aUniversityofWiscosion-MadisoncaseatamoderateReynoldsnumberandaJohnsHopkinsUniversitycaseatahighReynoldsnumber.Themodelusesanestimationofthesubgrid-scale(SGS)kineticenergytomodelthemagnitudeoftheSGSstresstensor,andusesthenormalizedvelocitygradienttensortomodelthestructureoftheSGSstresstensor.Testingisperformedforthefirstcasethroughacomparisonbetwee...

简介：周期性地强迫的空间地扩大的Brusselator在混乱政体被调查。我们探索在各种各样的强迫的频率和强迫的振幅下面产生的反响或非反响的模式。反响的空间地一致的摆动和不规则的结构被发现。而且，常规空间模式的二种类型在适当参数下面被产生。我们数字模拟的结果证明周期的力量能给上升在类似于常规摆动的强迫的系统的状况的空间与时间的混乱的强迫的系统撕了浊音模式。

简介：Mostcurrentcomputationsoftrubulentflowswithsecond-momentclosureadoptthediffusionmo-delswhichneglecttheeffectofpressure-velocitycorrelation.lnthepresentpapertheimportanceofthiscorrelationeffectiselucidatedtheneglectofthiseffectaccountsforsomemajordefectsinthewideapplicationofthese-cond-momentclosures.Throughtherelationbetweenand,establishedbyLumley,weproposehereanewturbulencediffusionmodelwhichtakesintoconsiderationthepressureeffect.Applicationsofthisnewmodelinthecomputationofshearlessturbulencemixinglayerandplane-andround-jetflowsshowthatthespreadingrateoftheseflowscanbesatisfactorilycaptured.

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简介：Inthispaper,wepresentanextensivestudyofthelinearlyforcedisotropicturbulence.Byusinganalyticalmethod,weidentifytwoparametricchoices,ofwhichtheyseemtobenewasfarasourknowledgegoes.WeprovethattheunderlyingnonlineardynamicalsystemforlinearlyforcedisotropicturbulenceisthegeneralcaseofacubicLienardequationwithlineardamping.WealsodiscussaFokker–Planckapproachtothisnewdynamicalsystem,whichisbistableandexhibitstwoasymmetricandasymptoticallystablestationaryprobabilitydensities.

简介：Ingasturbineengines,laminar-turbulenttransitionoccurs.However,generally,theturbulencemodelstodescribesuchtransitionresultsintooearlyandtooshorttransition.Combiningaturbulencemodelwithadescriptionofintermittency,i.e.thefractionoftimetheflowisturbulentduringthetransitionphase,canimproveit.Bylettinggrowtheintermittencyfromzerotounity,startandevolutionoftransitioncanbeimposed.Inthispaper,amethodwhereadynamicequationofintermittencycombiningwithatwo-equationk-ωturbulencemodelisdescribed.Thisintermittencyfactorisapremultiplicatoroftheturbulentviscositycomputedbytheturbulencemodel.FollowingasuggestionbyMenteretal.[1],thestartoftransitioniscomputedbasedonlocalvariables.