美赛培训论文.docx

美赛培训论文.docx

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FormationandVariationoftheGreatPacificGarbagePatch

Abstract

Inthispaper,webuildamodelbyutilizedynamicanalogtoexpoundtheformationoftheoceangarbagepatch.

Ourdestinationistotrackthelitterdebrisandforecastitsfutureconditionstohelpmanagingit.Aftertheanalysis,wefindthatthevelocityoftrashalleviatesastimegoeson.Trashdoesitsmotionintwoprobableways,oneisduetoresistancesgivenbyseawater,andanotherisduetodampedvibration.Byusingclassicphysicaltheories,wecapturemainmotivespropellingtrashintotheSouthPacificGyre.That’showthegreatgarbagepatchforms.

Accordingtothemodelandtheitsresult,weformulatethemonitoringprogram.

Comparedwiththephysicaltruth,themodelalsohassomeunsatisfactoryaspects,butithassomereference.

Introduction

Whereeveristheworld’slargestdump?

ItislocatedinthePacificOcean,aboutonethousandsixhundredkilometerswestofCalifornia,calledtheGreatPacificOceanGarbagePatch.Accordingtopertinentdata[1],itistenmilliontonsofdebrislitterthatispilingupthere,likeaplasticsoupwhenpeoplearelookingahead.And80percentofthetrashisfrommaincontinents,10percentconsistsofusednetsorotherfishingtoolsandtheother10percentoftrashisfrompassing-byships.Mostofthegarbageislandsareinoceanicgyres.Nowadays,awidevarietyoftechnicalandscientificproblemsassociatedwiththisdebrismassarecomingtolight.Butuntilnow,noonecanreasonoutit’scoverageareaexactlyandthegreateconomiclossesecologicalimpactandthePacificOceanGyrehascaused.

Long-termeffectivemethodsaresearchedtoobjectivelycharacterizetheGyre.TheoceancurrentisthemechanismoftheGreatPacificOceanGarbagePatch.Inourpaper,wewilltakethesouthpacificoceangarbagepatchforexample,focusingonhowthedebrislitterdriftsinthefluid,assemblesinquantity,distributesundertheeffectofoceancurrentsin.Afterwards,inaccordancewithourmodel,weprojectprocessreasonablesuggestionstomonitortheGyre,trackingit’sgrowth.

Assumptions

1.Regardlessoftimeandgeographicalposition’simpactsonthespeedoftheoceancurrents,weconsiderthespeedasconstantvalue.

2.Accordingtothedatum[2],wedesignatethespeedofthewestwinddriftvp1as1.4km/h,thatofPeruCurrentvp2as1km/h,thatofthesouthequatorialwarmcurrentasvp33km/h,thatofthenorthAustraliacurrentasvp41.4km/h.

3.RegardtheflowofthecurrentsasstationaryflowandtheseawaterasNewtonianfluid,whichmeanstheviscosityoftheseawaterisconstant.

4.Considertheleveloftheseaisinlaminarflow.

5.Themasspoint’smotionintheseacanbeinfluencedbytheoceancurrentnomatterhowfarthemallpointisawayfromit.

6.Themasspoint’smotionissynthesizedbythesub-movementofperoceancurrentregardlessofeffectsofotherfactors.

TheModel

Inourmodel,wewillutilizedynamicanalogtoexpoundtheformationoftheoceangarbagepatch.Themodelsubstitutesstraightlinesforoceancurrentswhichformthegyre,inthemodeltheorientationofthestraightlinerepresentativeoftheflowdirectionandthespeedvalueretrospecttotheassumptionNo.4.Sequentially,wesimplifythephysicaltruthasthatshowninthefigure1.（DuetothechangeofthedirectionofthePeruCurrentonpassage,thesimplifiedmodelreplacestowstraightlines,whichareofthesamespeedbutdifferentdirection,ofthePeruCurrent.）

Figure1:

theDistributionoftheOceanCurrentsintheSouthPacificOcean

Then,ourmodeltalksoverhowtheoceancurrenteffectthemasspoint’smovement,morespecifically,theeffectonthevelocityofthedirectionparalleltothelineandperpendiculartotheline.

Let’sdiscusstheeffectonthemasspoint’svelocityofthedirectionparalleltothelinefirstly.

AccordingtotheassumptionNo.3andNo.4andtherelativeinformation[3],wecandescribetheoceancurrentflowasone-dimensionalsteadyflow.OnthebasisofNavier-StokesEquationshowbelow

YmeansthemassforceofthedirectionY-axis,inourmodel;ρmeansthedensityofseawater;νmeansthekinematicviscosityofseawater,,μmeansthedynamicviscosityofseawater.Wecansimplifytheequationaboveandgettheonebelow

Integrateandget

（1）

Soweplugtowboundaryconditions

（2）shownbelowintotheformula

（1）

integralconstantisdetermined

Since,so

（2）

Wecanmakeaconclusionthatthemasspoint’svelocityinthedirectionparalleltotheoceancurrentisthesameasthatoftheoceancurrent.

Secondlywefocusonthemasspoint’velocityinthedirectionperpendiculartotheoceancurrent’sdirection.

Havingconsultedsomemate