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Wednesday 08 Oct 20142D models of convection-driven mean flows

Dr Laura Currie - University of Exeter

Physics, 4th floor 11:00-12:00

Large-scale mean flows have long been observed in many systems of astrophysical importance, such as planets, stars, galaxies and accretion disks. Despite this, mean flow generation is not a well understood process; neither is the interaction of mean flows with other physical processes such as magnetic field generation. Convection is an important mechanism in the driving of mean flows. To study the driving of such flows by convection, we consider nonlinear, rotating convection in a plane layer where the rotation vector is oblique to gravity, representative of different latitudes on a spherical body. We comment on the linear theory before presenting two-dimensional numerical simulations of mean flow generation in the nonlinear hydrodynamic and MHD regimes. In particular, we analyse the strength and vertical structure of the flows generated in the presence of: (i) a thermal wind, where the convection can either extract energy from the wind, or put energy into it; (ii) a vertical density stratification, making use of the anelastic approximation; and (iii) an imposed horizontal magnetic field, where it is a balance between the Reynolds and Maxwell stresses that determine the mean flows driven.

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