ntistotheleftoftheshockletfortheloweedsideofthelayer.iftheflowvelocityandsoundeedaredenotedbyu(t,x,y)anda(t,x,y)reectively,thent

heshockcanbedeterminedasthesetofthepointssatisfyingthefollowingrelation:
inwhich,εisacertainparameteranditsvaluewillaffectthenumericalthickneoftheshocklets.itwasfoundthatforourcasesavaluebetween0.005to0.01forεmightyieldgoodresults.then,εisfixedas0.01.u(t,x,y)anda(t,x,y)wereobtainedfromnumericalcomputation.itisconfirmedfromthecomputationthatifthemachnumberisnottoolarge,forawiderangeofra,themostutablet-swaveintroducedyieldedac≈1aspredictedbystabilityanalysis.thelocationofshockletsestablishedbythemethodaboveiscoistenttothedeestpartoftheiso-deitycontoursplot.
inordertomakeitevenmorereliable,oneeffectivemethodtoexaminewhetheritisashockletornotisasfollows:afterthelocationofashocklethasbeendeterminedby,say,theabovemethod,whichischangingwiththetime,onecanfollowafluidparticle,startingsomewherenearandinfrontoftheshocklet,toseetheentropychangeofthatparticle.theentropyoftheparticleremainedalmostunchangedwhenitdidnotmeettheshockletasinanadiabatic,isoentropicflow,butwouldunambiguouslyhaveanentropyjumpwhentheparticlepaedthroughtheshocklet.bythiscriterion,shockletsfoundbythepreviousmethodwereprovedtobecorrect.
2.theinfluencesofshockletsonflowcharacteristicsandtherelatiohipbetweenthestrengthofinducedshockletsandtheamplitudeofdisturbancetheinlethasbeenstudied.
inrecentyears,attemptshavebeenmadeinalyingthenonlineartheoryofhydrodynamicstabilitygoo

上一页  [1] [2] [3] [4] [5] [6] [7] [8] [9] 下一页