Analyzing a modulated electromagnetic m = 2 forcing and its capability to synchronize the large scale circulation in a Rayleigh-Bénard cell of aspect ratio Γ = 1

S. Röhrborn - P. Jüstel - P. Frick - V. Galindo - Th. Gundrum - F. Schindler - F. Stefani - R. Stepanov - T. Vogt

Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, Department of Magnetohydrodynamics, Bautzner Landstraße 400, 01328 Dresden, Germany

Abstract
The synchronization of the helicity of an instability with azimuthal wavenumber m = 1 by a weak tidal m = 2 perturbation might play a key role in explaining the phase-stable Schwabe cycle of the solar dynamo [1]. To elucidate this type of interaction, we study a thermally driven Rayleigh-Bénard convection under a tide-like influence. We focus first on the generation of the m = 2 mode flow by electromagnetic forcing and then on its low-frequency modulation. In the last section, we present preliminary results on the interaction of this perturbation with the sloshing/torsional motion of the Large Scale Circulation (LSC) of a Rayleigh-Bénard convection flow. While the main focus of the paper is on the numerical side, some comparisons with experimental results are also made. Figs 9, Refs 8.

Key words: Magnetohydrodynamics, Rayleigh-Bénard convection, liquid metal flow, electromagnetic forcing, CFD