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．Thusitisveryimportanttomakeadetailedresearchontheforcethatthef

2、luidmoleculesactonthemicro／nanoparticles．Inpresentwork，particleinthestationarygasenvironmentandinthestableflowfieldwereinvestigatedbyusingmoleculardynamicsmethod．ForBrownianparticleinthestationarygasenvironment，theforceactingontheparticlewasstudiedoverawiderangeofKnudsennumber(K

3、n)，theratiobetweenthefreepathandparticlediameter．Thespectrumanalysisshowsthat，theforcehavethefeatureof”preferentialfrequency”，namelythefrequencyoftheforcesactingontheBrownianparticleismainlyconcentratedaroundacertainfrequency．Meanwhile，theforcesalsoshowobvioussizeeffect，namelyth

4、emagnitudeoftheforcesignificantlyinfluencedbytheparticlesize：withthedecreaseofKn，theforceincreasestoapeakvalueandthengraduallydecreases．ThesizeeffectCandirectlyaffectthemotionoftheasymmetricalparticle，whichfitsexperimentallyrecordedparticlemotionintheliteraturewell．Formicro／nano

5、sizeparticlesinsteadyflowfield，thedragforceWasusuallycalculatedwithslipcorrectionoftheStokeslaw，suchastheCunninghalTlslipcorrection．Althoughithasbeenwidelyuseinpractice，theCunninghamslipcorrectionwasobminedinthehighspeedcircumstanceandtheperformanceinlowvelocityflowfieldisstilln

6、eedtobeverified．Inthispaper，thedragforceisfirstlystudiedforparticleinhigh—speedflowfields，theobtainednumericalresultsfitwellWiththeCunninghalTl’Sslipcorrection．Thefurtherstudiesonthedragforcewerecarriedoutforthemicro／nanoparticleinlowspeedflowfields，whicharecommonlymetinpractice

7、．TheresultsshowtheCunninghamcorrectioncannomoremakeaaccuratecalculmionofthedragforce．Anewcorrectionmethodwasgivenbasedonthenumericalresultsinourwork．III万方数据浙江大学硕士学位论文abstractDuetothelargenumberofmoleculesinthemodelling，computationcostincreasesexponentiallywiththeincreaseofnumber

8、ofmolecules．Inthiswork，wetakeadvantageofthehigh