Effect of Lateral Walls on the Onset of Convective Motions

Abstract

The critical Rayleigh number of a fluid layer confined in a box which is very thin in one horizontal direction and has lateral walls of finite thermal conductivity is studied theoretically. The lateral walls suppress the onset of convective motions not only mechanically but also thermally. The critical Rayleigh number, therefore, is far larger than that of a fluid layer, infinite in horizontal extent, 1708. The result coincides well with the experimental value obtained by Ukaji and Sawada (1969).