Lookup NU author(s): Dr Paul Bushby
Motivated by the interface model for the solar dynamo, this paper explores the complex magnetohydrodynamic interactions between convective flows and shear-driven instabilities. Initially, we consider the dynamics of a forced shear flow across a convectively stable polytropic layer, in the presence of a vertical magnetic field. When the imposed magnetic field is weak, the dynamics are dominated by a shear flow (Kelvin-Helmholtz type) instability. For stronger fields, a magnetic buoyancy instability is preferred. If this stably stratified shear layer lies below a convectively unstable region, these two regions can interact. Once again, when the imposed field is very weak, the dynamical effects of the magnetic field are negligible and the interactions between the shear layer and the convective layer are relatively minor. However, if the magnetic field is strong enough to favour magnetic buoyancy instabilities in the shear layer, extended magnetic flux concentrations form and rise into the convective layer. These magnetic structures have a highly disruptive effect upon the convective motions in the upper layer.
Author(s): Silvers LJ, Bushby PJ, Proctor MRE
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Date deposited: 06/01/2012
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Wiley-Blackwell Publishing Ltd.
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