Magnetohydrodynamic stability of stochastically driven accretion flows

Nath, Sujit Kumar and Mukhopadhyay, Banibrata and Chattopadhyay, Amit K (2013) Magnetohydrodynamic stability of stochastically driven accretion flows. In: PHYSICAL REVIEW E, 88 (1).

PDF ast_hig_ene_ast_phe-2013.pdf - Published Version Restricted to Registered users only Download (415kB) | Request a copy

Abstract

We investigate the evolution of magnetohydrodynamic (or hydromagnetic as coined by Chandrasekhar) perturbations in the presence of stochastic noise in rotating shear flows. The particular emphasis is the flows whose angular velocity decreases but specific angular momentum increases with increasing radial coordinate. Such flows, however, are Rayleigh stable but must be turbulent in order to explain astrophysical observed data and, hence, reveal a mismatch between the linear theory and observations and experiments. The mismatch seems to have been resolved, at least in certain regimes, in the presence of a weak magnetic field, revealing magnetorotational instability. The present work explores the effects of stochastic noise on such magnetohydrodynamic flows, in order to resolve the above mismatch generically for the hot flows. We essentially concentrate on a small section of such a flow which is nothing but a plane shear flow supplemented by the Coriolis effect, mimicking a small section of an astrophysical accretion disk around a compact object. It is found that such stochastically driven flows exhibit large temporal and spatial autocorrelations and cross-correlations of perturbation and, hence, large energy dissipations of perturbation, which generate instability. Interestingly, autocorrelations and cross-correlations appear independent of background angular velocity profiles, which are Rayleigh stable, indicating their universality. This work initiates our attempt to understand the evolution of three-dimensional hydromagnetic perturbations in rotating shear flows in the presence of stochastic noise.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW E
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copyright of this article is belongs to AMER PHYSICAL SOC
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	24 Sep 2013 08:35
Last Modified:	24 Sep 2013 08:35
URI:	http://eprints.iisc.ac.in/id/eprint/47301

Actions (login required)

View Item