简介：Alargeamountofexperimentalworkhasbeencarriedoutinthepasttounderstandmeanandfluctuatingforcesonasinglecircularcylinderincrossflows.Incomparisonsubstantiallylessworkcanbefoundontheinterferencebetweenmultiplecylindersandthenumberofpublicationsavailablebecomesdrasticallysmallerasthenumberofcylindersinvolvedincreases.Thecurrentexperimentalworksystematicallyexaminesthewakeshieldingeffectsofthreecylindersinatowingtank.Thoughstaggered,thethreecylindersarearrangedmainlyalongtheflowdirectionwiththedownstreamcylinderssituatinginthewakesoftheupstreamcylinders.Thetestsaremainlycarriedoutinthesub-criticalReynoldsnumberregimewiththeupperendclosetothecriticalReynoldsnumberregime.Significantdragreductionondownstreamcylindersisidentified.

简介：ＶＩＳＣＯＵＳ　ＳＣＡＬＥ　ＥＦＦＥＣＴＳ　ＯＮ　ＰＲＯＰＥＬＬＥＲ　ＴＩＰ　ＶＯＲＴＥＸ　ＣＡＶＩＴＡＴＩＯＮＶＩＳＣＯＵＳＳＣＡＬＥＥＦＦＥＣＴＳＯＮＰＲＯＰＥＬＬＥＲＴＩＰＶＯＲＴＥＸＣＡＶＩＴＡＴＩＯＮ￥ＹｅＹｕａｎ－ｐｅｉ；ＬｕＦａｎｇ；Ｓ...

简介：Theshearviscosityofturbulentdrag-reducingsurfactantsolutionwasmeasuredasafunctionofconcentration,shearrateandtemperaturebyusinganAG-G2rheometer(TAInstruments,NewCastle,USA).Theexperimentalresultsshowedcomplicatedrheologicalbehaviorwiththeconcentrationinlarge.TheBird-Carreaumodelwasfoundtofitwelltothemeasuredrheologicalresults.Thecharacteristicsfortheparametersη0,η∞andλdependenceontemperaturewerealsostudied.

简介：Alongwiththeflourishingofthewindenergyindustry,floatingoffshorewindturbineshavearousedmuchinterestamongtheacademiaaswellasenterprises.Inthispaper,theeffectsofthesupportingplatformmotionontheaerodynamicsofafloatingwindturbinearestudiedusingtheopensourceCFDframeworkOpenFOAM.Theplatformmotionresponses,includingsurge,heaveandpitch,aresuperimposedontotherotationofthewindturbine.Thrustandtorqueonthewindturbinearecomparedandanalysedforthecasesofdifferentplatformmotionpatternstogetherwiththeflowfield.Itisshownthatthemovementofthesupportingplatformcanhavelargeinfluencesonafloatingoffshorewindturbineandthusneedstobeconsideredcarefullyduringthedesignprocess.

简介：Aparalleldirect-forcingfictitiousdomainmethodisappliedinfully-resolvednumericalsimulationsofparticle-ladenturbulentflowsinasquareduct.Theeffectsoffinite-sizeheavyparticlesonthemeansecondaryflow,themeanstreamwisevelocity,theroot-mean-squarevelocityfluctuation,andtheparticleconcentrationdistributionareinvestigatedatthefrictionReynoldsnumberof150,theparticlevolumefractionof2.36%,theparticlediameterof0.1ductwidth,andtheShieldsnumberrangingfrom1.0to0.2.Ourresultsshowthattheparticlesedimentationbreakstheup-downsymmetryofthemeansecondaryvortices,andresultsinastrongersecondary-flowcirculationwhichtransportsthefluidsdownwardinthebulkcenterregionandupwardalongthesidewallsatalowShieldsnumber.Thiscirculationhasasignificantimpactonthedistributionofthemeanstreamwisevelocity,whosemaximumvalueoccursinthelowerhalfduct,unlikeintheplanechannelcase.Theflowresistanceisincreasedandtheturbulenceintensityisreduced,astheShieldsnumberisdecreased.Theparticlesaccumulatepreferentiallyatthefacecenterofthebottomwall,duetotheeffectofthemeansecondaryflow.Itisobservedthatthecollisionmodelhasanimportanteffectontheresults,butdoesnotchangetheresultsqualitatively.

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简介：Inthiswork,weperformanumericalstudyofawaterflowoverasteppedspillway.ThisflowisdescribedbytheReynoldsaveragedNavier-Stokesequation(RANS)associatedwiththeturbulencek-εmodel.Theseequationsaresolvedusingacommercialsoftwarebasedonthefinitevolumeschemeandanunstructuredmesh.Theair-waterflowwasmodeledusingvolumeoffluid(VOF)andmultiphasicmethods.Thecharacteristicsoftheflowwereinvestigatedincludingthetotalpressure,thevelocityprofile,etc..Weanalyzetheeffectsontheflowstructureofthestepsandcountermarchinclination,theairinjectionthroughthecountermarchintothewaterflowandthedynamicswaterdischarges.Resultsshowthattheinclinationofthecountermarchrelativetotheverticalandtheairinjectionintothewaterflowincreasethetotalpressureintheneighbourhoodofthesteps.

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简介：Avariablecoefficient,rotation-modifiedextendedKortweg-deVries(vReKdV)modelisappliedtothestudyoftheSouthChinaSea(SCS),withfocusontheeffectsofthehigh-order(cubic)nonlinearityandtherotationonthedisintegrationprocessoflarge-amplitude(170m)InternalSolitaryWaves(ISWs)andthesemi-diurnalinternaltidepropagatingfromthedeepbasinstationtotheslopeandshelfregionsinacontinuouslystratifiedsystem.Thenumericalsolutionsshowthatthehigh-ordernonlinearitysigni-ficantlyaffectsthewaveprofilebyincreasingthewaveamplitudeandthephasespeedinthesimulatedarea.ItisshownthattheinitialKdV-typeISWwilldecayfasterwhentherotationdispersionisconsidered,howeverthewaveprofiledoesnotchangesignificantlyandtherotationeffectisnotimportant.Thesimulationsofthesemi-diurnalinternaltideindicatethatthephaseofthewaveprofileisshiftedearlierwhentherotationeffectisincluded.Asolitarywavepacketemergesontheshelf,andthewavespeedisalsogreaterwhenconsideringtherotationdispersion.Inaddition,theeffectsofthebackgroundcurrentsarediscussedfurtherinthispaper.ItisfoundthatthebackgroundcurrentsgenerallychangethemagnitudeandoccasionallychangethesignofthenonlinearcoefficientsinthenorthernSCS.

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

简介：Physicalmodeltestswerecounductedtopredictlocalscourandmaximumscourdeptharoundthelargediametercylinderslocatedinthe(sand)seabedundertheactionofbothwaveandcurrent.Accordingtotheresultoftests,ananalysiswasmadeonallthefactorsinfluencingthescour.Theresultsshowsthatfortheseabedwithrelativefinegrainsinshallowwater(0.07＜h/L≤0.28),whentherelativediameterD/Lofthecylinderiswithin0.3-0.7,themaineffectivescourfactorsaroundthecylinderintheseabedarediameterDofthecylinder,thewaveheightH,thewavelengthL,thevelocityVcofthecurrentandtheparametersrelatedtotheseabedsoiltexture.Themainparametersinfluecingthemaximumscourdepthwereanalyzed,andthetestdataweresyntherized,toobtaintheformulapredictingthescourdeptharoundthelargediametercylinderundertheofbothwaveandcurrent.

简介：Channelconfluencesareuniversallypresentinnature.Theycanbedividedintotwotypes:asymmetricalriverconfluencesandsymmetricriverconfluences.ThelatterisalsocalledastheY-shapedconfluences.Mostofpreviousworkhaspaidmoreattentiontotheasymmetricalriverconfluences,butfewstudieshavebeenconductedontheY-shapedconfluences.Inthisarticle,theeffectsofbeddiscordanceontheflowpatternsat'Y'shapedopen-channelconfluenceswerestudiedbyusinga3-Dnumericalsimulation.Itisprovedthatthemodelcanundertakequantitativeassessmentoftheflowatconfluences.TheresultsindicatethattherearealotofdifferencesbetweentheY-shapedconfluenceandasymmetricalconfluence.ThediscordantbedheightplaysanimportantroleattheY-shapedjunction.