简介：Athree-stepfiniteelementmethod(FEM)togetherwithLargeEddySimulation(LES)isap-pliedtoincompressibleturbulentflowaroundseabedpipelinesatrelativelyhighReynoldsnumbers.Bothtwo-dimensionalandthree-dimensionalnumericalsimulationiscarriedouttodeterminethethree-dimensionaleffect.Theresultsofnumericalsimulationagreequitewellwiththewaveforcesactingonpipelinemodelsmeasuredinphysicalmodeltest.

简介：Three-dimensionelectronicchartdisplayinformationsystem(ECDIS)isoneofthenewdevelopingdirectionsofelectronicnavigationchart,anditsreal-timequalityisoneoftheimportantrequirements.Inthispaperthealgorithmofsimplifyingtrianglesurfaceusingedgecontraction,whichcanensurethereal-timedisplayofobjectsinseabedenvironment,wasputforward.TheoptimumcontractionpointwasdeterminedbytheLagrangematrix,sothatthealgorithmensuresthatthecontractionpointlocatesontheoriginalmodel,meanwhilemeetsthedemandsofleastdeviation.Thisalgorithmcanimprovetheplottingspeed,andpreservetheboundarycharacterbyusingthefewertrianglestosimulateobjects.

简介：Realisticsimulationofunderwatersceneisalwaysdifficultbecauseofthespecialandcomplexvisioneffectsinunderwaterspace.Seabedisanimportantpartofunderwaterenvironment.ThispaperdescribesthemethodsforseabedscenesimulationbasedonOpenGL.Itincludesconstructionoffluctuantterrainbasedontherandomsinusoidalalgorithm,simulationofseabedflickereffectbymeansofcirculartexturemappingandgenerationofturbidityeffectbyusingfogtechniques.Fortheapplicationbasedontheleadinghighlevel3Ddevelopmentenvironment-Vega,underwaterscenesimulationisstilladifficultysincethereisnomoduleforit.BasedontheanalysisofVegasoftwareandtheresearchonseabedscenesimulationmethods,aVegaextendingmodulenamed'UnderwaterSpace'wascreatedthroughdevelopingmoduleclassandextendinglynxinterface.ThemoduleclasswasdesignedthroughdevelopingDLLwritteninC++.TheLynxwasextendedthroughdevelopingkeywordconfigurefile,GUIconfigurefileandlynxplug-inDLL.TheproblemthatVegacan'tsimulateunderwaterspace,iselementarilyresolved.Theresultsshowthatthismoduleisefficient,easyusing,andtheseabedsceneimagesarevivid.

简介：BasedonBiot'sconsolidationtheory,atwo-dimensionalmodelforcomputationoftheseabedresponsetowavesispresentedwiththefiniteelementmethod.Numericalresultsfordifferentwaveconditionsareobtained,andtheeffectsofwavenon-linearityonthewave-inducedseabedresponseareexamined.Moreover,thewave-inducedmomentaryliquefactioninuniformandinhomogeneousseabedsisinvestigated.Itisshownthatthewavenon-linearityaffectsthedistributionofthewave-inducedporepressureandeffectivestresses,whiletheinfluenceofwavenon-linearityontheseabedliquefactionpotentialisnotsosignificant.

简介：Wave-inducedtransientresponseofdisplacements,effectivestressesandporepressureinsaturateseabedaresalvedbyaconsolidationfiniteelementmethod.Theinfluenceoftheresponsestothestabilityofseabedandcoastalstructuresisshownbyanimprovedslicemethodwithcirculararcslipsurface.Dynamicelasticconsolidationtheoryandlinearpermeabilitytheoryareemployedinthesolutionofseabedresponse.Theseabedcanbeconsistedoflayeredsoilwitharbitraryboundaries.Theactingwavecanberegularorirregular.Irregularwavepressureactingonthesurfaceofseabediscalculatedbylinearsuperpositionmethod.Wave-inducedexcessstressontheslipsurfaceisconsideredinthestabilityanalysis.Thespatialandtemporalvariationsofporepressureinsandyseabedcomparewellwithexperiment.Calculationsforaverticalbreakwatershowthatthesafetyfactorofseabedandstructurewilldecreaseifwave-inducedseabedresponseisconsidered.Thescopeofdecreaseismainlyre

简介：-Thecyclicrotationofprincipalstressdirectionwithaconstantamplitudeisthecharacteristicsofcyclicstressinseabeddepositinducedbytravellingwaves.Presentedinthepaperaretheresultsobtainedfromtestssimulatingthecyclicstresscharacteristics,withemphasislaidonthebuildupofporewaterpressureinsoilsamples.Regressionanalysisoftestdatashowsthattheporewaterpressurecanbeexpressedasthefunctionofthenumberofcyclesofcyclicloading,orasthefunctionofgeneralizedshearstrain.Usingtheresultsthusobtained,thepossibilityoffailureofseabeddepositundercyclicloadinginducedbytravellingwavescanbeevaluated.Thecomparisonwiththeresultsofconventionalcyclictorsionalsheartestsshowsthatneglectoftheeffectofthecyclicrotationoftheprincipalstressdirectionwillresultinconsiderableover-estimationofthestabilityofseabeddeposit.

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