简介:Inthisstudy,wenumericallyinvestigatedthenonlinearfocusedwavegroupactiononatruncatedsurface-piercingstructure,anddevelopedatwo-dimensionalfullynonlinearnumericaltankusingthehigher-orderboundaryelementmethod.WedeterminedtheamplitudeofthewavecomponentsofthefocusedwavegroupbasedontheJONSWAPwavespectrum.Wediscusstheeffectsofthepresenceofasurface-piercingstructureonthecharacteristicsofthefocusedwavegroupandfindthatthelocationofthestructuredoesnotevidentlychangethefocallocationorfocaltimeofthefocusedwavegroup.Thelargestamplitudesoftherun-upandhorizontalforceonthestructureoccurwhenthefrontsurfaceofthestructureisatthefocallocation.Thecriticaldraughtandbreadthofthestructureoccurwhenthewaverun-upreachesitsmaximumalongthestructure.
简介:流动在在水的免费表面附近移动的轮船壳附近产生的表面波浪在这研究数字地被模仿。三维的含蓄的有限体积方法(FVM)被使用解决雷纳兹平均海军司烧(RANS)方程。可实现的k-e骚乱模型被实现了在免费表面地区在轮船壳附近捕获狂暴的流动。方法结合了的液体(VOF)的体积Stokes波浪理论被用来决定水的免费表面效果。由使用是一自由的六度当模特儿,轮船壳运动数字地一起与Stokes波浪被解决。在行动下面司烧海,在空气之间的接口和在一样的常规模式并且那么的水波浪上的波浪做压力和垂直速度。轮船壳搬到象波浪的一样的方法。轮船壳举的振幅是不到波浪高度因为抑制的粘性。这个方法能为轮船运动,波浪和水动力学的学习提供一本重要参考书。
简介:Thehydrodynamicanalysisofmulti-floatingbodiesisimportantandwidelyusedinmarineengineering.Inthisstudy,wesystematicallysimulatedthewavediffractionproblemofafixedverticalfour-cylinderstructureinregularwavesinthetimedomaininaviscousnumericalwavetank.Thehydrodynamicinteractionofwaveswithabottom-mountedstructureconsistingoffourverticalcylindersarrangedatthecornersofasquareshowsacomplicatedinterferencephenomenon.Inthispaper,weillustrateandanalyzetherun-uparoundthestructureandthecorrespondingwaveforces.Toinvestigatetheviscouseffectonthenear-trappingphenomenon,wepayparticularattentiontoinvestigatingthewavesnear-trappedinsidethefour-cylinderstructure,andmakeacomparativestudyoftheviscous-andinviscid-flowsolutionswiththeexperimentalmeasurements.Theresultsshowthatthemaximumwaveelevationoccursontheinnersideoftheleesidecylinder,andthatthewaveelevationsontheoutersideofthecylindersarelowerthanthoseontheinnerside.Wecanconcludethatviscosityhasanobviousdampingeffectonwaveelevationsinsidethestructure.Thecylindersshowatendencytodriftapartfromeachotherwhenthenear-trappingphenomenonoccurs.
简介:弄平的粒子水动力学(SPH)是一个Lagrangian无网孔的粒子方法。然而,它内核近似的低精确性当粒子是分布式的时在边界附近混乱或定位是以它的宽应用程序的方法站的一个障碍。采用泰勒系列扩大方法并且解决不可分的方程矩阵,第二个顺序核近似方法能被获得,也就是K2_SPH,它在这份报纸被讨论。这个方法类似于有限粒子方法。与核近似的改进,一些数字技术应该为边界的不同类型被采用,例如一条免费表面边界和稳固的边界,它是为水波浪模拟的K2_SPH的二种关键数字技术。这份报纸给一些涉及由使用K2_SPH承受波浪和sloshing坦克问题的二维的水波浪模拟的数字结果。从模拟结果的比较,K2_SPH方法比标准SPH更可靠。
简介:Theaddedmasscoefficientandthewaterlevelindexformulasforthesame-phaseandanti-phasevibrationofrectangularliquidtanks'bulkheadswerederivedbasedondrymodetheory.Threefluid-structureinteractionnumericalmethodsincludingFluidFEMandFluidBEMwereusedinthiscase.ThecomparisonofnumericalandtheoreticalresultsbythepresentmethodshowsthatANSYS/FluidS0ismorecredible,theNASTRAN/VirtualMassMethodismoresuitableforengineeringcalculationsandresultsofthesame-phasevibrationbythepresentmethodismoreaccurate.
简介:在这份报纸,进附近的结构上的水和他们的效果里的远域爆炸波浪的繁殖的调查被执行。为远域结构,包围结构的液体的运动可以被假定小,允许管理液体方程的linearization。这个问题的完全的分析必须在包围液体包含结构和爆炸波浪的繁殖的动态反应的同时的答案。在这研究,一个动态适应有限元素过程被建议。它到一个2D液体结构相互作用的解决方案的应用程序在时间域被调查。研究包括:一)计算远地散布波浪由于在水下看情况时间的声学的波浪方程的爆炸包括答案,b)用联合Euler-Lagrangian途径的液体结构相互作用分析,和c)适应有限元素过程采用错误估计,并且重新协调。时间的网孔改编被格子的本地新生基于压力功能的弯曲用时间依赖者错误指示物完成。作为结果,全面反应被一个动人的网孔更好比一个相等的一致网孔预言。另外,当精确性被改进时,为大问题的计算的费用被减少。
简介:Commoneffectofwaveandslipofinternalheavyloadwillmakerollingoftheroll-onshipserious.Thisisoneoftheimportantreasonsforoverturnofro-roships.ThemultibodiesSystemwithafloatingbaseiscomposedofro-roshipandslippingheavyload.Thispapertakestherollingangleoftheshipandthetransversedisplacementoftheheavyloadondeskastwofreedoms.Makinguseofanalysisofapparentgravitationandapparentbuoyancy,thewaverollingmomentisderived.Byuseofdynamicmethodofmultibodiessystemwithafloatingbase,dynamicequationsofthesystemareestablished.Takingacertainchannelferryasanexample,asetofnumericalcalculationhavebeencarriedoutforrollingresponseoftheshipanddisplacementresponseoftheslippingheavyloadundercommoneffectofsynchro-slippingheavyloadsandwave.
简介:S-surfacecontrolhasproventobeaneffectivemeansformotioncontrolofunderwaterautonomousvehicles(AUV).Howevertherearestillproblemsmaintainingsteadyprecisionofcourseduetotheconstantneedtoadjustparameters,especiallywheretherearedisturbingcurrents.Thusanintelligentintegralwasintroducedtoimproveprecision.AnexpertS-surfacecontrolwasdevelopedtotunetheparameterson-line,basedontheexpertsystem,itprovidesS-surfacecontrolaccordingtopracticalexperienceandcontrolknowledge.Topreventcontroloutputover-compensation,afuzzyneuralnetworkwasincludedtoadjusttheproductionrulestotheknowledgebase.ExperimentswereconductedonanAUVsimulationplatform,andtheresultsshowthattheexpertS-surfacecontrollerperformsbetterthananS-surfacecontrollerinenvironmentswithcurrents,producinggoodsteadyprecisionofcourseinarobustway.
简介:Arraycalibrationisimportantinengineeringpractice.Inthispaper,fastcalibrationmethodsforaULA'sgainandphaseerrorsbothinfarandnearfieldsareproposed.Inthefarfield,usingasinglesoundsourcewithoutexactorientation,thismethodhorizontallyrotatesthearrayexactlyonce,performseigenvaluedecompositionforthecovariancematrixofreceiveddata,thencomputesthegainandphaseerroraccordingtotheformulas.Inthenearfield,usingthesamesinglesoundsource,itisnecessarytorotatethearrayhorizontallyatmostthreetimes,buildequationsaccordingtogeometricrelations,thensolvethem.Usingtheformulaproposedinthispaper,sphericalwavesaremodifiedintoplanewaves.Theneigenvaluesdecompositionisperformed.Thesetwocalibrationmethodswereshowntobevalidbysimulationandarefast,accurateandeasytouse.Finally,ananalysisoffactorsinfluencingestimationprecisionisgiven.
简介:Oceanographicsurvey,orothersimilarapplicationsshouldbetheapplicationsofmultipleAUVs.Inthispaper,theskill&simulationbasedhybridcontrolarchitecture(S2BHCA)asthecontroller'sdesignreferencewasproposed.Itisamulti-robotcooperationorientedintelligentcontrolarchitecturebasedonhybridideas.TheS2BHCAattemptstoincorporatethevirtuesofthereactivecontrollerandofthedeliberativecontrollerbyintroducingtheconceptofthe"skill".Theadditionalonlinetasksimulationabilityforcooperationissupported,too.Asanapplication,amultipleAUVcontrolsystemwasdevelopedwiththree"skills"fortheMCMmissionincludingtwodifferentcooperativetasks.Thesimulationandtheseatrialsshowthatsimpletaskexpression,fastreactionandbettercooperationsupportcanbeachievedbyrealizingtheAUVcontrollerbasedontheS2BHCA.