Magnetohydrodynamic stability of stochastically driven accretion flows


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. © 2013 American Physical Society.

Publication DOI:
Divisions: Engineering & Applied Sciences > Mathematics
Engineering & Applied Sciences > Systems analytics research institute (SARI)
Uncontrolled Keywords: cross-correlations,magneto-hydrodynamic flow,magnetohydrodynamic stability,magnetorotational instability,radial coordinates,rotating shear flow,temporal and spatial,weak magnetic fields,angular velocity,astrophysics,autocorrelation,energy dissipation,magnetohydrodynamics,stochastic systems,shear flow,Condensed Matter Physics,Statistical and Nonlinear Physics,Statistics and Probability
Full Text Link: http://journals ... sRevE.88.013010
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2013-07-17
Authors: Nath, Sujit K.
Mukhopadhyay, Banibrata
Chattopadhyay, Amit K. ( 0000-0001-5499-6008)



Version: Accepted Version

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