简介：Basedonthe2ndordercnoidalwavetheory,thecharactersofshallowwaterstandingwavesandtheiractiononverticalwallsarestudiedinthispaper.Thetheoreticalexpressionsofthewavesurfaceelevationinfrontofandthewavepressureontheverticalwallareobtained.Inordertoverifythetheoreticalresults,modeltestsweremadeintheStateKeyLaboratoryofCoastalandOffshoreEngineeringatDUT.Forthewavesurfaceelevationinfrontofthewallandthewaveforcesonthewallatthemomentwhenthewavesurfaceatthewallsurfacegoesdowntothebottomofthewavetrough,thecalculatedresultscoincidequitewellwiththeexperimentalresults.Forthewaveforcesonthewallatthemomentwhenthewavesurfaceatthewallsurfacegoesuptothetopofthewavecrest,thetheoreticalexpressionsaremodifiedbytheexperimentalresults.Fortheconvenienceofpracticaluse,calculationsaremadeforthewaveconditionswhichusuallyoccurinengineringpracticebyuseoftheinves

简介：Inthispaper,thecharacteristicsofdensitycurrentundertheactionofwavesaredescribedwiththehelpofflumeexperimentandtheoreticalanalysis.Thestudyshowsthatturbidwaterundertheac-tionofthewavescanpresentthreetypesofmotion,i.e.significantstratification,fragilestratificationandstrongmixing.Themotionofturbidwaterpresentssignificantstratificationwhen（H/D）/△ρ/ρ1/2≤4.5,generallythisstateisknownasdensitycurrent.Theformulasofmotionvelocity,thickness,anddischargeofdensitycurrentmovingonhorizontalbottomarederivedbyuseofba-sicequationssuchasmomemtumequation,equationofenergyconservationandcontinuityequationoffluid.Thetime-averagevelocityandthethicknessofdensitycurrentundertheactionofwaveshavearela-tionshipwithsuchparametersasrelativedensity（△ρ/ρ）,waveheight（H）,andwaterdepth（D）.Whentheseparametersaredetermined,thetime-averagethicknessandmotionvelocityofdensitycurrentareal-sodetermined.Therelat

简介：-Thehydrodynamiccoefficientsforeachoftwopilesandthreepilesinbothside-by-sidearrangementandtandemarrangementundertheactionofirregularwavesareexperimentallyinvestigated.ThesecoefficientsvarywiththeKCnumber,therelativepilespacing,thenumberofpilesandthepilelocation,andtheirrelationshipsarepresentedinthispaper.TheycanbeusedinMorisonEquationandotherequationstocalculatedirectlythein-linewaveforcesandthetransverseforcesoneachpileinarray.

简介：Basedonthetime-domainhigher-orderboundaryelementmethod（HOBEM）,atwo-dimensionalnumericalwaveflumeisdevelopedtoinvestigatesolitarywaveinteractionwithtworectangularboxeswithanarrowgap.Inthenumericalmodel,thefullynonlinearboundaryconditionsaresatisfiedonthefreesurface,themixedEulerian-Lagrangianmethodisadoptedtotrackthetransientwatersurfaceandthefourth-orderRunga-Kuttamethodisusedtopredictthevelocitypotentialandwaveelevationonthefreesurface.Theaccelerationpotentialtechniqueisusedtocomputethetransientwaveforcesalongthewettedobjectsurface.Apiston-typewavemakerisusedtogeneratesolitarywaves.Theproposedmodelisvalidatedbycomparingthesimulatedwaverun-upandthewaveloadswiththepublishedexperimentalandnumericalresultsofthereflectionofasolitarywavefromaverticalwall.Then,numericalexperimentsareperformedtostudytheeffectsofthenarrowgapandthesizeofeachboxonthewaverun-upsatthetwosidesofthetwo-boxsystemandinthenarrowgapbetweentwoboxes,andthewaveloadsonthetwoboxes.Theinteractionbetweendoublesolitarywaveswithatimeintervalbetweenthemwithatwo-boxsvstemisalsoinvestigated.

简介：-ThisarticleisaimedattheexperimentalstudyofthehydrodynamicloadinginducedbywavesandcurrentactingontheJZ20-2submarinecompositepipelines.Thecorrespondinghydrodynamiccoefficientsobtainedinthisexperimentalstudycanbeappliedtoengineeringprojects.

简介：Withtheincreaseofpetroleumandgasproductionindeepocean,marinerisersofcircularcylindershapearewidelyusedintheoffshoreoilandgasplatform.Inordertoresearchthehydrodynamicperformanceofmarinerisers,thedynamicmeshtechniqueandUser-DefinedFunction(UDF)areusedtosimulatethecircularcylindermotion.Themotionofatransverselyoscillatingcircularcylinderincombinationofuniformflowandoscillatingflowissimulated.Theuniformflowandoscillatingflowbothareinxdirection.SIMPLEalgorithmisusedtosolvetheNavier-Stokesequations.TheUser-DefinedFunctionisusedtocontrolthecylindertransversevibrationandtheinletflow.Theliftanddragcoefficientchangingwithtimeandthemapofvorticityisolinesatdifferentphaseangleareobtained.ForcetimehistoriesareshownforuniformflowatReynoldsnumber(Re)of200andforthecombinationofuniformandoscillatingflows.Withtheincreaseofamplitudeofoscillatingflowincombinedflow,thechangeofliftamplitudeisnotsensitivetothethechangeofcylinderoscillatingfrequency.Liftamplitudeincreaseswiththeincreaseofoscillatingflowamplitudeinthecombinedflow,butthereisnodefiniteperiodicityoftheliftcoefficient.Thedragandinertiaforcecoefficientschangewhenthemaximumvelocityoftheoscillatingflowincreasesinthecombinedflow.Thevortexsheddingnearthecircularcylindershowsdifferentcharacteristics.

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简介：Ascientifichypothesisisproposedandpreliminarilyverifiedinthispaper:underthedrivingofseepageflows,theremightbeaverticalmigrationoffine-grainedsoilparticlesfrominteriortosurfaceofseabed,whichisdefinedas‘sub-bottomsedimentpumpaction’inthispaper.FieldexperimentswereperformedtwiceontheintertidalflatoftheYellowRiverdeltatostudythisprocessviabothtrappingthepumpedmaterialsandrecordingtheporepressuresinthesubstrate.Experimentalresultsarequiteinterestingaswedidobserveyellowslurrywhichismainlycomposedoffine-grainedsoilparticlesappearingontheseabedsurface;seepagegradientswerealsodetectedintheintertidalflat,undertheactionoftidesandsmallwindwaves.Preliminaryconclusionsarethat‘sedimentpump’occurswhenseepageforceexceedsacertainthreshold:firstly,itisbigenoughtodisconnectthesoilparticlesfromthesoilskeleton;secondly,thedegreeofseabedfluidizationorbioturbationisbigenoughtoprovidepreferredpathsforthedetachedmaterialstomigrateupwards.Thentheywouldbefirstlypumpedfrominteriortothesurfaceofseabedandtheneasilyre-suspendedintooverlyingwatercolumn.Influentialfactorsof‘sedimentpump’aredeterminedashydrodynamics(waveenergy),degreeofconsolidation,indexofbioturbation(permeability)andcontentoffine-grainedmaterials(sedimentaryage).Thisnewperspectiveof‘sedimentpump’mayprovidesomeimplicationsforthemechanisminterpretationofseveraluncleargeologicalphenomenaintheYellowRiverdeltaarea.