简介:Whenabodynavigateswithcavityinshallowwater,bothflexiblefreesurfaceandrigidbottomwallwillproducegreatinfluencesonthecavityshapeandhydrodynamicperformances,andfurtheraffectthemotionattitudeandstabilityofthebody.Inthepresentwork,characteristicsofthenaturalcavitatingflowarounda2-Dsymmetricalwedgeinshallowwaterwereinvestigatedandtheinfluencesoftwotypeboundariesontheflowpatternwereanalyzed.TheVolumeOfFluid(VOF)multiphaseflowmethodwhichissuitableforfreesurfaceproblemswasutilized,coupledwithanaturalcavitationmodeltodealwiththemass-transferprocessbetweenliquidandvaporphases.Withintherangeofthecavitationnumberforcomputation(0.07-1.81),thecavityconfigurationswouldbedividedintothreetypes,viz.,stabletype,transitiontypeandwake-vortextype.Inthisarticle,theshapesofthefreesurfaceandthecavitysurface,andthehydrodynamicperformanceofthewedgewerediscussedundertheconditionsofrelativelysmallcavitationnumber(<0.256).Thepresentnumericalcavitylengthsgenerallyaccordwithexperimentaldata.Whenthecavitationnumberwasdecreased,thecavitywasfoundtobecomelongerandthicker,andthescopeofthedeformationofthefreesurfacealsograduallyextends.Thefreesurfaceandtheuppercavitysurfacecorrespondfairlytotheirshapes.However,thelowersideofthecavitysurfacewasratherleveledduetotheinfluenceofwallboundary.Theliftanddragcoefficientsofthis2-Dwedgebasicallykeeplinearrelationswiththenaturalcavitationnumbersmallerthan0.157,whereasdirectproportionfordragandinverseproportionforlift.
简介:Inpastterroristattacks,vehicleborneimprovisedexplosivedevices(VBIED)havebeentheprimarymannerofattackingbuildingsandinfrastructures.Preventingunauthorizedvehiclesfromapproachingaprotectedareawithanti-ramsystemswouldmaintainanestablishedstandoffdistanceagainstmovingandstationaryvehiclesandconsequentlyreduceblastanddebristhreats.Thisstrategyhasbeenconsideredthefirstlineofdefenceagainstterrorists.Severaltypesofanti-ramdeviceshavebeendevelopedinaccordancewithU.S.DepartmentofStateK-ratingcriteria,forexample,wedgebarriers,risingbeams,sliding/swinggates,anddroparms.However,thesedevicestypicallyneedadeepfoundationforinstallationandcan'tbeimplementedintomanylocationswhereadepthofexcavationislimitedinordertoprotectutilitylinesofbuildingsandinfrastructures.Thispaperpresentsarecentdevelopmentofaseriesofshallowfootinganti-rambollardsystems(SFABS)thatcansatisfyK-12ratingwithonlyfive-inchthickfooting.Ahigh-fidelityphysicsbasedfiniteelementtechniquewithavehiclecrashmodelisusedforpredictinganti-ramcapacityanddeterminingdesignparametersoftheSFABS.Full-scalevehiclecrashtestsofthedevelopedSFABSsystemshavebeencarriedouttovalidatethedesignandanalysis.
简介:平均深度的流动污染物质联合了的A2D模型基于空铅树网孔被建立精确地在这篇论文与不规则的自然边界在水区域模仿流动。格子被递归的分关于播种点产生。一个发现newneighbor算法被介绍。管理方程是在由越过在房间之间的接口使用有限的卷方法,和质量,动量和污染物质的正常流动的并置的保守变量的discretized被一个Godunov类型流动DifferenceSplitting(FDS)计划计算。模型被使用在一条腹股沟附近模仿流动地。计算的值与观察数据一致。结果显示空铅树网孔有好本地分辨率,高效率和容易的本地精炼。当适用于复杂流动领域时,空铅树格子模型能在效率提供获得,是清楚的或强壮砍流动。最后,模型在江苏HaizhouBay被用于流动地和集中地模拟。模仿的弄脏的区域与观察被匹配很好。因此,这个模型能被用来与不规则的自然土地边界预言实际的水区域的流动和集中地。
简介:Shallowwaterflow(SWF),adisastrousgeohazardinthecontinentalmargin,hasthreateneddeepwaterdrillingoperations.Underoverpressureconditions,continualflowdeliveringunconsolidatedsandsupwardintheshallowlayerbelowtheseafloormaycauselargeandlong-lastinguncontrolledflows;theseflowsmayleadtocontrolproblemsandcausewelldamageandfoundationfailure.Eruptionsfromover-pressuredsandsmayresultinseafloorcraters,mounds,andcracks.Detailedstudiesof2D/3DseismicdatafromaslopebasinoftheSouthChinaSea(SCS)indicatedthepotentialpresenceofSWF.Itiscommonlycharacterizedbylowerelasticimpedance,ahigherVp/Vsratio,andahigherPoisson'sratiothanthatforthesurroundingsediments.AnalysisofgeologicaldataindicatedtheSWFzoneoriginatedfromadeepwaterchannelsystemwithgasbearingover-pressuredfluidflowandahighsedimentationrate.WeproposedafluidflowmodelforSWFthatclearlyidentifiesitsstressandpressurechanges.TheruptureofpreviousSWFzonescausedthefluidflowthatoccurredintheBaiyunSagofthenorthernSCS.
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简介:Green-Naghdi(G-N)理论是为水波浪的一个充分非线性的理论。一些研究人员把它称为一个充分非线性的Boussinesq模型。G-N理论的复杂性的不同的度被在哪儿的鈥渓evels鈥?区分越高水平,越多复杂并且大概更精确理论。在这里介绍的研究,比较在G-N理论的二个不同层次之间被做,明确地铺平II并且铺平IIIG-N限制理论。限制理论被给的水平IIIG-N的一个线性分析解决方案。一个平面沙滩上的波浪和变浅的波浪两个都与这二个G-N理论被模仿。水平IIIG-N也限制了理论罐头,这第一次被显示出被用来在浅水里预言液体速度。水平IIIG-N限制了理论被推荐而不是水平IIG-N限制理论当模仿时,充分非线性的浅水飘动。关键词Green-Naghdi理论-Boussinesq模型-充分非线性的水飘动-变浅的波浪基础条款:在资助号码50779008和111工程(B07019)下面由中国的国家自然科学基础支持了。箱箱赵在1984出生了。他是一会儿在哈尔滨工程的液体力学的一个博士候选人大学。他的当前的研究兴趣基于BEM包括Green-Naghdi理论和非线性的波浪身体相互作用。Wen-yangDuan在1967出生了。他在设计大学的哈尔滨是一个教授和一个博士监督人。他的当前的研究兴趣包括非线性的波浪身体相互作用,SPH方法和Boussinesq模型。
简介:在华南海(SCS)的浅南方的翻发行量(MOC)的低频率的可变性为19002010的时期用一个简单海洋数据吸收(苏打)产品被调查。一个动态分解方法在MOC在哪个被分解成Ekman被使用,外部模式,并且垂直砍部件。结果证明所有三个动态部件在SCS贡献季节、年度的吝啬的浅MOC的形成。在SCS的浅MOC由二个房间组成:一顺时针方向在南方的房间和在北方的一个逆时针方向的房间;前者被Ekman流动控制,后者被外部barotropic流动统治,与贡献垂直砍是减少两个房间的大小。另外,在南方的MOC的力量被发现在过去的世纪有一个掉落的趋势,主要对一变弱减少外部部件的运输的吕宋岛海峡运输(LST)到期。进一步的分析建议变弱LST是仔细与一在赤道的太平洋上变弱西的风异例有关,它导致向北赤道的水流(NEC)分叉并且这样的向南方的移动吕宋岛的自台湾东面的菲律宾海流向日本的暖流东方的更强壮的运输。
简介:Waveforcesactingontheoffshorestructureareofimportanceforthestructuredesignpointofview.Thereisasocalled'TwoTensionLegBuoyMooringSystem'designedtoopenuptheoilfieldinSouthChinaSea.Twobasesofthesystemaresittingontheseafloorof30-40metersdepthofwater.Inordertoconfirmthesafetyofthissystem,waveforcesareinvestigatedexperimentallyandnumerically.Nowadays,themeasuredmaterialsonthissubjectarescarce.InthemodeltestofDr.Chakrabarti,thetestset-upnecessitatedasmalluniformgapbe-tweenthemodelandtankfloor,andthecorrectresultsmustbecomefromanadjustment.Theauthorshavesolvedtheproblem.Inthepaper,twonumericalmethodsareadopted:3-Dboundaryintegralequationmethod)eigen-functionexpressionandmatchingmethod.TheformerconsistsofdistributionofHaskindGreen’functiononthebodysurface.Thelatter,however,bydividingthewholefluiddomainintosubregions,thevelocitypotentialforeachsubregionscanbedetermineduniquelybymatchingthevelocitypotentialontheircommonboundaries,whichwasexpressedformallybyitseigenfunctionexpansion.Asanexample,experimentalandnumericalresultsweregivenforacircularbaseinshallowsea.Theyagreequitewell.Althoughbothmethodsareeffective,thematchingmethodhasmoreefficiency.