简介：Freesurfaceflowproblemsinvolvinglargefreemotionsareanalysedusingfiniteelementtechniques.InsolvingtheseproblemsanArbitraryLagrangian-Eulerian(ALE)kinematicaldescriptionofthefluiddomainisadopted,inwhichthenodalpointscanbedisplacedindependentlyofthefluidmotion.Anewmeshtracingmethodisproposedinthispaper.Toconfirmtheeffectivenessofthenewmethod,solitarywavepropagationisanalysedandthenumericalresultsarecomparedwiththeanalyticalresults.ThebehaviouroftheviscousfluidflowwithafreesurfaceisexpressedbytheunsteadyNavier-Stokesequation.Fornumericalintegrationintimethevelocitycorrectionfractionalstepmethodisused.

简介：ByanalyzingturbulencedatameasuredattwositesincoastalregionsofHangzhoubay,itisdiscoveredthat:(1)TheturbulentintensityI_kisinverselyproportionaltothewindspeedatlowerspeed.Whileathigherwindspeed,itkeepsbasicallytobeconstant.(2)Undertheunstableconditionsinthevicinityofseashore,thedimensionlessstandarddeviationsofwindspeedσ_k/U(?)areconstantsbasically,whileintheinland,theycanbedescribedbytheexpressionssimilartoPanofsky(1977)modelsbutwithdifferentconstants.Underthestableconditions,theyareconstantswhenZ/L<0.2andproportionalto1/3powerofZ/LforlargerZ/L.(3)Nearthecoast,thevariationofU(?)/UwithZ/LfollowsBusinger(1971)modelU(?)/U=k/(?)(Z/L)verywellnotonlyunderstablebutalsounderunstablecondition.Inland,itiscoincidentverywellmerelyunderthecondition-1.0≤Z/L≤0.3.Outthisrange,thedeviationislarge.(4)ThedispersionparameterscanbedescribedintheformrecommendedbyDraxler(1976)butwithdifferentconstants.Undertheunstablecondition,theycanalsobeexpressedasBriggs(1985)modelwithdifferentconstants.

简介：垂直地在免费表面上侵犯的一口2D槽喷气的流动特征被大埃迪模拟(LES)数字地与一个动态Sub-GridScale(SGS)模型一起调查。σ-坐标转变被介绍印射深度变量物理领域到一件深度制服计算领域。裂口操作员计划，把答案过程切成移流，散开和压力繁殖步，被采用解决即时速度和压力地。一个充分非线性的Lagrange-Euler方法被用来计算免费表面举起。数字结果证明喷气在Eestablished流动(ZEF)的地区保留你方类似，当喷气的骚乱逐渐地变从时对各向同性在表面冲击(ZSI)的地区各向异性。当喷气接近免费表面时，中心线速度很快减少并且流动被免费表面偏斜。二口对称的表面喷气在水平喷气(ZHJ)的地区被形成。超高的AnapproximateGuassian分发也在免费表面上被形成。Thecomputed结果在对可得到的试验性的数据的好同意。

简介：ＵＮＳＴＥＡＤＹＰＲＯＰＥＬＬＥＲＳＵＲＦＡＣＥＰＲＥＤＩＣＴＩＯＮＷＩＴＨＡＰＯＴＥＮＴＩＡＬＢＡＳＥＤＰＡＮＥＬＭＥＴＨＯＤ￥ＣｈｅｎＪｉａ－ｄｏｎｇ（ＣｈｉｎａＳｈｉｐＳｃｉｅｎｔｉｆｉｃＲｅｓｅａｒｃｈＣｅｎｔｅｒ，Ｂｏｘ１１６，Ｗｕｘｉ２１...

简介：Thispaperhaspredictedtherangeandvolumeofunsteadysheetcavitationofapropellerbyusingthesurfacepanelmethod.Thelinearizationincavitythicknessisadoptedtoreducethecomputingtimeandstoragespace.Theiterationschemebetweenchordwisestripshasbeenusedbecausetherangeandvolumeofcavitationarebothunknown.Thepropellercavitationrangedeterminedbythecalculationmethodpresentedinthispaperagreeswiththeobservationresultsofcavityimageatcavitationtunnelverywell,andthisprovesthepracticabilityofthemethod.

简介：BasedonTianetal.'stheoreticalmodelofmicrowavescattering,byusingthewindwavespectrumsuggestedbyFungetal.,numericalresultsofpolarizedback-scatteringwerecalculated.Thequantitativerelationshipsbetweenthecalculatedbackscatteringcross-sectionandtheenvironmentalparameters,suchaswindspeeds,azimuthalanglesandincidenceangles,werestudied.Comparedwiththetraditionaltwo-scalescatteringmodel,theresultsaremuchmorecoincidentwiththeobservationsundertheconditionofmoderateincidenceangles,whichisveryusefultomakeupforthetwo-scalemodel.Tomakethenewcalculationmodeltobeusedconvenientlyinthepractice,itssimplifiedformwasproposed.

简介：Athree-dimensionalmathematicalmodelforcalculatingthesteadyflowofcircularnon-buoyantturbulentsurfaceinacoflowingchannelispresentedinthispaper.Forclosingthecontrolequations,theκ-εturbulencemodelisusedinthemathematicalmodel.Thewall-functionmethodisemployedtotreatthewallboundaryconditionatthebottomplane.TheclosedcontrolequationsarediscretizedbyusingHybridFiniteAnalyticMethod(HFAM)onanon-uniformstaggeredgridsystem.Thenumericalresultsareobtainedfordifferentratioofthejetvelocitytothecoflowingvelocity.Thecomparisonwithexperimentaldatashowsgoodagreement.

简介：TheturbulenceflowFreeSurfacehasimportantapplicationsinhydraulicspillwaysstructure,suchasthehydraulicjump,energydissipationflowetc.Thisisbeingconsideredasverycomplicatedflow,andhasnotyetbeensolvedquitewellbynumericalmethod.Inthispaper,aLarge-scalecomputationalsoftwarepackagearedevelopedfornumericallaboratoryofhydraulicspillwaystructure.Somemethods,suchasturbulencemodel,freesurfaceandirregularboundarytreatingtechniques,scientificcomputervisualizationareputforwardandperformed.

简介：AraisedpanelmethodbasedonNURBS(Non-UniformRationalB-Splines)forfree-surfaceflowswithforwardspeedispresented.Inthisgeneralizedpanelmethod,NURBSareemployedtorepresentthebodygeometry,disturbedfreesurface,andtoexpresstheunknownsourcestrengthdistribution,onthebodysurfaceandabovethefreesurface.Comparedwithcommonhigher-orderpanelmethods,ithasnoneedofadoptinglocalcoordinates.NURBSmakethegeometryrepresentationofthebodyshapeandthewavepatternmoreprecise.Raisedpanelsabovethefreesurfaceproducelessnumericaldispersionerror,needlessCPUconsumptionandarehelpfulandcombinedwithcollocation-pointshiftingup-stream,cansatisfytheradiationconditionnumerically.ByusingcontinuousanddiscreteFourieranalysis,numericalerrorsofthismethodarediscussedandageneralexpressionfortheerrorsofnumericaldampinganddispersion,includingtheeffectsoftheverticaldistanceofsingularitiestothefreesurface,theorderofsingularitydistributionrepresentedbyB-splinesinpanels,andcollocation-pointshiftingisderived.

简介：Inthispaperthecomplexstructureandpatternofshipsternflowdrivenbymulti-propellersissimulatednumericallybyusingRANSequationswithK-εturbulencemodelandpropellerliftingsurfacetheoryasessentialresearchtoolandcouplingthecomputercodeofshipsternflowtothecomputercodeofpropellerperformancepredictionthroughthemediumofbodyforce.Ashipmodelwithfourpropellersisselectedasthenumericalexample.Detailedcomputationalresultsarepresentedgraphicallyandthequalitativeandquantitativeanalysisismade.Finally,thecomparisonbetweenthecalculatedresultandtheavailableexperimentaldataismade.Theagreementbetweenthemissatisfactory.

简介：Thecut-offnegativepressuremethodisoneofeffectiveapproachestosolvetheseepageflowwithfreesurface.Accordingtothecharacteristicsofthismethod,however,ithasbeenfoundoutthatthedeficiencyofthealgorithmsistoeasilycauseinaccuratesimulationinthevicinityoffreesurfaceowingtothepenaltyfunctionwithonlyonecontrollingpenaltyparameter.Therefore,animprovedcut-offpressuremethodwaspresentedbyconstructingpenaltyfunctionwithtwocontrollingpenaltyparameters.Theimprovedalgorithmswereillustratedtobeabletoimprovethesimulationaccuracyandraisetheconvergencespeedthroughconsideringtheeffectsofthepartiallysaturatedorunsaturatedelementsmorereasonablyandcalculatingthenodalexternalforcesmoreaccurately.Finally,theimprovedcut-offnegativepressuremethodwasappliedtothesimulationofunsteadyseepageflowwithfreesurface,andthecorrespondingprogramcodesweredevelopedwithvalidationofsomecases.

简介：Betaeffectsonsurfaceflowsinarotatingannuluswitharadialtemperaturegradientandaslopingbottomwerestudiedexperimentally.AnazimuthaljetwasproducedbytheactionoftheCoriolisforceintheconvectiveregionbetweenthetwosidewallsoftheannulus.Propagatingvelocityandpatternsofthebaroclinicwaveonthesurfacewereobtainedbyusingafrequency-meterandastreakphotographrespectively.Itisshownthatthereexiststhenonlinearinteractionbetweenthebaroclinicandbetaeffects.Thebetaeffectexertslittleinfluenceonthestratificationflowsandconstrainsthebaroclinicinstability,anditpromptstheinstabilityoftheweakstratificationflowsandresultsinthesurfacepatternofwaveswithhigherfrequency.Itisalsoindicatedthatthebetaeffectcanreducethepropagatingspeedofthesurfacewavesinthejet,andincreasethethermalRossbynumberforthosesamesurfacepatternsunderagivenTaylornumber.

简介：Makingfulluseoffunctionalvariationswithvariabledomainforhandlingboththefreesurfaceandunknownpartofthedamwall,afamilyofvariationalprinciples(VPs)forthehybrid(direct-inverse)problemoffreesurfacespillwayflowundergravityisformulatedintermsofthepotentialfunctionΦ.Thistheoryoffersnewrationalandversatilewaysfordamde-signandasoundtheoreticalbasisfornumericalsolution,e.g.bythefiniteelementmethod(FEM).

简介：Inthepresentpaper,two-andthree-dimensionalvelocitypotentialsgeneratedbypulsatingpressuredistributionsofinfiniteextentonthefreesurfaceofinfinite-depthwatersarestrictlyderivedbasedonspecialcasesofconcentratedpulsatingpressure.Thefar-fieldasymptoticbehaviourofthepotentialsandtheradiationconditionstobesatisfiedbythemarediscussed.Itisprovedinageneralsensethatthepotentialsshouldbecomposedofaforcedwavecomponent,afreewavecomponentandalocaldisturbancecomponent.Theradiationconditionoftheforcedwavecomponentshouldcorrespondtothefar-fieldasymptoticbehaviourofthepressuredistribution,Hence,theformulationofradiationconditionsforthesecond-orderdiffractionpotentialshastheoreticallybecomeclear,Theradiationconditionsfortwo-andthree-dimensionalproblemsareexplicitlygiveninthepaper.