流场中微纳颗粒受力特性的分子动力学模拟-研究

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1、万方数据浙江大学硕士学位论文abstractAbstractMicro／nanoparticletwo—phaseflowwidelyexistsinnatureandengineering．Atthesametime，itcausesmanyproblemssuchashaze，carexhaustandspreadofdisease．Theforceactingontheparticledeterminesitsmotion．Thusitisveryimportanttomakeadetailedresearcho

2、ntheforcethatthefluidmoleculesactonthemicro／nanoparticles．Inpresentwork，particleinthestationarygasenvironmentandinthestableflowfieldwereinvestigatedbyusingmoleculardynamicsmethod．ForBrownianparticleinthestationarygasenvironment，theforceactingontheparticlewasstud

3、iedoverawiderangeofKnudsennumber(Kn)，theratiobetweenthefreepathandparticlediameter．Thespectrumanalysisshowsthat，theforcehavethefeatureof”preferentialfrequency”，namelythefrequencyoftheforcesactingontheBrownianparticleismainlyconcentratedaroundacertainfrequency．Me

4、anwhile，theforcesalsoshowobvioussizeeffect，namelythemagnitudeoftheforcesignificantlyinfluencedbytheparticlesize：withthedecreaseofKn，theforceincreasestoapeakvalueandthengraduallydecreases．ThesizeeffectCandirectlyaffectthemotionoftheasymmetricalparticle，whichfitse

5、xperimentallyrecordedparticlemotionintheliteraturewell．Formicro／nanosizeparticlesinsteadyflowfield，thedragforceWasusuallycalculatedwithslipcorrectionoftheStokeslaw，suchastheCunninghalTlslipcorrection．Althoughithasbeenwidelyuseinpractice，theCunninghamslipcorrecti

6、onwasobminedinthehighspeedcircumstanceandtheperformanceinlowvelocityflowfieldisstillneedtobeverified．Inthispaper，thedragforceisfirstlystudiedforparticleinhigh—speedflowfields，theobtainednumericalresultsfitwellWiththeCunninghalTl’Sslipcorrection．Thefurtherstudies

7、onthedragforcewerecarriedoutforthemicro／nanoparticleinlowspeedflowfields，whicharecommonlymetinpractice．TheresultsshowtheCunninghamcorrectioncannomoremakeaaccuratecalculmionofthedragforce．Anewcorrectionmethodwasgivenbasedonthenumericalresultsinourwork．III万方数据浙江大学

8、硕士学位论文abstractDuetothelargenumberofmoleculesinthemodelling，computationcostincreasesexponentiallywiththeincreaseofnumberofmolecules．Inthiswork，wetakeadvantageofthehigh