Vertical Structure of Magnetohydrodynamic Turbulence in Accretion Disks

Publications of the Astronomical Society of Japan

Nakao, Yasushi¹ 

[1]Department of Astronomy, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-01

关键词: "Accretion disks";    Magnetohydrodynamics;    Turbulence;   

DOI  :  10.1093/pasj/48.2.335

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

Theverticalstructureofmagnetohydrodynamicturbulenceinaccretiondiskswithdensitystratificationisconsideredbyapplyingone-pointclosuremodelingoftheturbulence.Thetransportequationsofturbulentkineticenergy(K),turbulentmagneticenergy(KW),anddensityvariance(KD)aresolvedsimultaneouslyundertheassumptionsofisothermaldisksandnoglobalmagneticfield.Moreover,theturbulenceinthediskisassumedtobehomogeneousinthehorizontalplane.Theimposedboundaryconditionsare:(i)boththeturbulentenergyKandthedensityvarianceKDdonotescapefromthediskthroughthesurface;(ii)ontheotherhand,theescapeofturbulentmagneticenergyKWisconsideredphenomenologically.TheresultsshowthatbothKandKW/ρM(magneticenergyperunitmass)increasewithheightduetoturbulentdiffusion.Itfollowsthattheso-calledα-valuegenerallyincreasesfromtheequatorofdiskstowardthesurface,thoughitdecreases,duetotheescapeofmagneticfields,inaregionratherclosetothesurface.Theresultsfurthershowthatthemagneticenergyislargerthantheturbulentkineticenergyoverawiderangeofthediskheight,implyingthatthemaincontributortoangular-momentumtransportandviscousheatinginthedisksisthemagneticfields.

【 授权许可】

Unknown