简介:NonlinearMHDKelvin-Helmholtz(K-H)instabilityinapipeistreatedwiththederiva-tiveexpansionmethodinthepresentpaperThelinearstabilityproblemwasdiscussedinthepastbyChandrasekhar(1961)andXuetal.(1981).Nagano(1979)discussedthenonlinearMHDK-Hinstabilitywithinfinitedepth.Heusedthesingularperturbationmethodandextrapolatedtheob-tainedsecondordermodifierofamplitudevs.frequencytoseekthenonlineareffectontheinstabilitygrowthrateγ.However,inourview,suchanextrapolationisinappropriate.Becausewhentheinstabili-tysetsin,thegrowthratesofhigher,ordertermsontherighthandsideofequationswillexceedthecor-respondingsecularproducingterms,sotheexpansionwillstillbecomemeaninglessevenifthesecularproducingtermsareeliminated.Mathematicallyspeaking,it’simpossibletoderiveformula(39)whenγ02isnegativeinNagano’spaper.Moreover,evenasearlyasγ02→O+,theexpansionbe-comesinvalidbecausethe2ndordermodifierγ2(inhisformula(56))tendstoinfinity.Thisweak-nessisremovedinthispaper,andtheresultisextendedtothecaseofapipewithfinitedepth.
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简介:Non-lineardevelopmentofdoubletearingmodesinducedbyelectronviscosityisnumericallysimulated.MHDflowlayersaredemonstratedtomergeinthedevelopmentofthemodes.Theshearedflowsareshowntoliejustattheboundariesofthemagneticislands,andtohavesuffcientlevelsrequiredforinternaltransportbarrier(ITB)formation.PossiblecorrelationbetweenthelayerformationandtriggeringofexperimentallyobservedITBs,preferentiallyformedinproximitiesofrationalfluxsurfacesoflowsafetyfactors,isdiscussed.
简介:Anewmethodforconstructingthesymmetricformforthehyperbolicsystemsisintroduced.ThenanewsymmetricformoftheequationsofMHDtransverseflowisconstructedbyaddinganadditionalequation.Withthisnewform,weobtainthelocalexistenceofsmoothsolutionincludingthecasethattheinitialdensitymaytendtothevacuumstateatinfinity.Furthermore,theuniformlyaprioriestimationfortheclassicalsolutionsisestablishedandtheglobalsmoothsolutionsforakindofinitialdataareobtained.
简介:Inlostpaperofmagneto-hydrodynamicinstabilityanalysisofliquidmetalfreesurfacejetflow(PartⅠ),themagneto-hydrodynamicinstabilitywasanalyzedforthejetflowinatransversenon-uniformmagneticfield,BT.But,asallknown,fortherealconditionsofliquidmetallimiter-divertorplasma-facingcomponentsareintoroidalandpoloidalfields.So,wetrytoanalyzethemagneto-hydrodynamicinstabilityofthejetflow(herebyonlyforcircularshapecrosssectionjetflow)inthezoneofnon-uniformmagneticfields,