简介:Wavediffractionoftwoconcentricporouscylinderswithvaryingporositywasstudiedbyusingananalyticalmethodbasedoneigenfunctionmatching.Thefluiddomainaroundthecylindersisdividedintothreesub-domainsandineachsub-domainaneigenfunctionexpansionofthevelocitypotentialisobtainedbysatisfyingtheLaplaceequation,theboundaryconditionsonthefreesurfaceandontheseabed.Theunknowncoefficientsofeigenfunctionexpansionsaredeterminedbyboundaryconditionsontheporoushulls.Inthepaper,theboundaryconditionsarebasedupontheassumptionthattheflowintheporousmediumisgovernedbyDarcy’slaw.Twoporous-effectparametersappliedontwoporouscylindersarefunctionsoftheverticalcoordinateinsteadoftheconstant.Waveloadingontheouterandinnercylinderispresentedinthenumericalresults.
简介:Toprovideasimulationsystemplatformfordesigninganddebuggingasmallautonomousunderwatervehicle’s(AUV)motioncontroller,asix-degreeoffreedom(6-DOF)dynamicmodelforAUVcontrolledbythrusterandfinswithappendagesisexamined.Basedonthedynamicmodel,asimulationsystemfortheAUV’smotionisestablished.ThedifferentkindsoftypicalmotionsaresimulatedtoanalyzethemotionperformanceandthemaneuverabilityoftheAUV.InordertoevaluatetheinfluencesofappendagesonthemotionperformanceoftheAUV,simulationsoftheAUVwithandwithoutappendagesareperformedandcompared.TheresultsdemonstratetheAUVhasgoodmaneuverabilitywithandwithoutappendages.