Thermocapillary instabilities in a laterally heated liquid bridge with end wall rotation
Résumé
The effect of rotation on the stability of thermocapillary driven flow in a laterally heated liquid
bridge is studied numerically using the full-zone model of the floating-zone crystal growth
technique. A small Prandtl number (0.02) fluid, relevant for semiconductor melts, is studied with
an aspect ratio (height to diameter of the melt) equal to one. Buoyancy is neglected. A linear
stability analysis of three-dimensional perturbations is performed and shows that for any ratio of
angular velocities, a weak rotation rate has the surprising effect of destabilizing the base flow. By
systematically varying the rotation rate and ratio of angular velocities, the critical threshold and
azimuthal wave number of the most unstable mode is found over a wide range of this two
parameter space. Depending on these parameters, the leading eigenmode is a wave propagating
either in the positive or negative azimuthal direction, with kinetic energy typically localized close
to one of the end walls. These results are of practical interest for industrial crystal growth
applications, where rotation is often used to obtain higher quality crystals.