简介:Inthisstudy,thepassageofwavesthroughpilegroupswithdifferentarrangementsisinvestigatedusingathree-dimensional(3D)numericalmodel.Forthesimulations,wavesofthreedifferentheightsof36,58,and81mm,afixedperiodof0.88s,andafixedwavelengthof1.128mwereused.Tosimulatethewavesandflowpatternthroughthepiles,Reynolds-averagedNavier–Stokes(RANS)equationsoffluidmotionweresolvedbasedonthefinitevolumemethod(FVM).Pilesweredefinedasobstaclesintherectangulardomainusingthefractionalarea/volumeobstaclerepresentation(FAVOR)method.Thevolume-of-fluid(VOF)andre-normalizationgroup(RNG)methodswereusedtosimulatethefreesurfaceandturbulencephenomenon,respectively.Byperformingdifferentnumericalsimulations,theeffectofcoastalpilearrangementsonwavepatternwasstudiedandwascomparedwithexistingexperimentaldata,andanacceptableagreementwasachieved.
简介:Inthispaper,a3Dsourcedistributiontechniqueisusedtocalculatethecoupledmotionsbetweentwoshipswhichadvanceinthewavewiththesamespeed.Thenumericalresultsofcoupledmotionsforafrigateandasupplyshiphaveagoodagreementwiththeexperimentalresults.Basedonthe3Dcoupledmotionsoftwoships,aspectralanalysisisemployedtoclearlyobservetheeffectofspeed,clearanceandwaveheadingonthesignificantrelativemotionamplitude(SRMA)oftwoships.Themethodpresentedinthispaperwillbehelpfultoselectsuitableclearance,speedandwaveheadingforunderwayreplenishmentatsea(RAS).
简介:Green-Naghdi(G-N)theoryisafullynonlineartheoryforwaterwaves.SomeresearcherscallitafullynonlinearBoussinesqmodel.DifferentdegreesofcomplexityofG-Ntheoryaredistinguishedby"levels"wherethehigherthelevel,themorecomplicatedandpresumablymoreaccuratethetheoryis.IntheresearchpresentedhereacomparisonwasmadebetweentwodifferentlevelsofG-Ntheory,specificallylevelIIandlevelIIIG-Nrestrictedtheories.AlinearanalyticalsolutionforlevelIIIG-Nrestrictedtheorywasgiven.WavesonaplanarbeachandshoalingwaveswerebothsimulatedwiththesetwoG-Ntheories.ItwasshownforthefirsttimethatlevelIIIG-Nrestrictedtheorycanalsobeusedtopredictfluidvelocityinshallowwater.AlevelIIIG-NrestrictedtheoryisrecommendedinsteadofalevelIIG-Nrestrictedtheorywhensimulatingfullynonlinearshallowwaterwaves.
简介:Inthepresentwork,computationalsimulationswasmadeusingANSYSCFXtopredicttheimprovementsinfilmcoolingperformancewithdualtrench.Dual-trenchconfigurationconsistsoftwotrenchestogether,onewidertrenchandtheotherisnarrowtrenchthatextrudedfromthewiderone.Severalblowingratiosintherange(0.5:5)wereinvestigated.Thepitch-to-diameterratioof2.775isused.Byusingthedualtrenchconfiguration,thecoolantjetimpactedthetrenchwalltwotimesallowingincreasingthespreadingofcoolantlaterallyinthetrench,reducingjetvelocityandjetcompletelycoveredonthesurface.Theresultsindicatethatthisconfigurationincreasedadiabaticeffectivenessasblowingratioincreased.Thespatiallyaveragedadiabaticeffectivenessreached57.6%foratM=2.Noobservedfilmblow-offatallblowingratios.Theadiabaticfilmeffectivenessofdualtrenchcaseoutperformedthenarrowtrenchcase,laidbackfan-shapedhole,fan-shapedholeandcylinderholeatdifferentblowingratios.
简介:Thispaperpresentsanimprovedunstructuredgridimmersedboundarymethod.Theadvantagesofbothimmersedboundarymethodandbodyfittedgridswhicharegeneratedbyunstructuredgridtechnologyareusedtoenhancethecomputationefficiencyoffluidstructureinteractionincomplexdomain.TheNavier-StokesequationwasdiscretizedspaciallywithcollocatedfinitevolumemethodandEulerimplicitmethodintimedomain.TherigidbodymotionwassimulatedbyimmersedboundarymethodinwhichthefluidandrigidbodyinterfaceinteractionwasdealtwithVOS(volumeofsolid)method.AnewVOScalculationmethodbasedongraphwaspresentedinwhichbothimmersedboundarypointsandcrosspointswerecollectedinarbitraryordertoformagraph.Themethodisverifiedwithflowpastoscillatingcylinder.
简介:鳍和控制的运动出现在水下在液体的车辆是一个有趣、挑战性的研究题目。典型地在如此的身体附近的液体流动上的鳍摆动的效果是高度不稳定的,产生旋涡并且要求液体结构相互作用的详细分析。如此的流动的复杂性的理解在他们的推进开发能够高有活力的性能的车辆并且调遣的工程师感兴趣。在现在的学习,CFD基于搬进来的3-D鳍身体的RANS模拟一粘滞液体被开发。它由评估水动力学系数调查了水动力学性能(电梯,拖并且时刻)在二不同震荡频率。影响鳍身体的水动力学性能的因素的参量的分析被做,与从实验的结果的比较一起。模拟的结果在对试验性的结果的靠近的同意被发现,这为3-D鳍的不稳定的水动力学系数的评估作为一个有效工具验证了模拟。这个工作能是进一步的被用于稳定性的分析和激活的鳍的可操作性在水下车辆。
简介:Thenumericalmodellingoftheinteractionsbetweenwaterwavesandfloatingstructuresissignificantfordifferentareasofthemarinesector,especiallyseakeepingandpredictionofwave-inducedloads.SeakeepinganalysisinvolvingsevereflowfluctuationsisstillquitechallengingevenfortheconventionalRANSmethod.Particlemethodhasbeenviewedasalternativeforsuchanalysisespeciallythoseinvolvingdeformableboundary,wavebreakingandfluidfragmentationaroundhullshapes.Inthispaper,theweaklycompressiblesmoothedparticlehydrodynamics(WCSPH),afullyLagrangianparticlemethod,isappliedtosimulatethesymmetricradiationproblemforastationarybargetreatedasaflexiblebody.Thisiscarriedoutbyimposingprescribedforcedsimpleharmonicoscillationsinheave,pitchandthetwo-andthree-nodedistortionmodes.Theresultant,radiationforcepredictions,namelyaddedmassandfluiddampingcoefficients,arecomparedwithresultsfrom3-Dpotentialflowboundaryelementmethodand3-DRANSCFDpredictions,inordertoverifytheadoptedmodellingtechniquesforWCSPH.WCSPHwerefoundtobeinagreementwithmostresultsandcouldpredictthefluidactionsequallywellinmostcases.
简介:在靠近的最近的二漂浮结构很通常在近海的设计被看见。他们经常受到陡峭的波浪并且因此,他们的水动力学特征上的短暂效果担心大。这份报纸使用伪任意的Lagrangian-Eulerian有限元素方法(QALE女性)基于充分非线性的潜在的理论(FNPT),组织自由(DOF)的度数字地调查在二3-D漂浮之间的相互作用,它与6经历运动,并且与不同事件角度受到波浪。漂浮的结构,伴随的结构的效果,和运动和波浪上的非线性的短暂行为结构上的负担是学习的主要焦点。调查揭示一引起更加更大的结构的重要短暂效果处于稳定的状态比那打手势。结果也显示在靠近的最近的伴随的结构在引起第二顺序部件具有到基本的类似的意义的更强壮的非线性提高在不同运动模式和结果之间的相互作用。