A unifying picture of helical and azimuthal magnetrotational instability, and the universal significance of the Liu limit

Kirillov, Oleg, Stefani, Frank and Fukumoto, Yasuhide (2012) A unifying picture of helical and azimuthal magnetrotational instability, and the universal significance of the Liu limit. The Astrophysical Journal, 756 (1). p. 83. ISSN 0004-637X

[img]
Preview
Text
2012APJ-KSF.pdf - Published Version

Download (517kB) | Preview
Official URL: http://dx.doi.org/10.1088/0004-637X/756/1/83

Abstract

The magnetorotational instability (MRI) plays a key role for cosmic structure formation by triggering turbulence in the rotating flows of accretion disks that would be otherwise hydrodynamically stable. In the limit of small magnetic Prandtl number, the helical and the azimuthal versions of MRI are known to be governed by a quite different scaling behavior than the standard MRI with a vertical applied magnetic field. Using the short-wavelength approximation for an incompressible, resistive, and viscous rotating fluid, we present a unified description of helical and azimuthal MRI, and we identify the universal character of the Liu limit for the critical Rossby number. From this universal behavior we are also led to the prediction that the instability will be governed by a mode with an azimuthal wavenumber that is proportional to the ratio of axial to azimuthal applied magnetic field, when this ratio becomes large and the Rossby number is close to the Liu limit.

Item Type: Article
Uncontrolled Keywords: instabilities, magnetohydrodynamics (MHD) , waves
Subjects: F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Oleg Kirillov
Date Deposited: 10 Jan 2017 11:30
Last Modified: 10 May 2017 12:07
URI: http://nrl.northumbria.ac.uk/id/eprint/29040

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics


Policies: NRL Policies | NRL University Deposit Policy | NRL Deposit Licence