Thermocapillary instabilities in liquid metal: Hartmann number versus Prandtl number

J. Priede - A. Thess - G. Gerbeth

Abstract
We consider the effect of a vertical magnetic field on the hydrothermal wave instability of thermocapillary driven shear flow of an electrically conducting fluid in a horizontal three-dimensional planar layer. The linear stability analysis is confined to the disturbances traveling crosswise the basic flow. It is shown that the critical Reynolds number increases with the square of the strength of the applied magnetic field, while the wavelength of the most unstable mode is inversely proportional to the field strength. In low Prandtl number fluids an increasing magnetic field can change the instability mechanism so that it partially resembles the instability occurring in high Prandtl number fluids. Figs 6, Refs 10.