PATTERN SELECTION FOR THE OSCILLATORY ONSET IN THERMOSOLUTAL CONVECTION

A layer of fluid lies between two parallel horizontal walls and the so lute concentration and temperature are higher at the bottom wall. The onset of time-periodic instability in this double diffusion problem in three dimensions is analyzed. Periodicity with respect to the hexagon al lattice is assumed. The no-slip condition is imposed at the top and bottom boundaries. There are 11 bifurcating solutions, and their stab ility is presented. For relatively low solutal and thermal Rayleigh nu mbers, the solutions are found to be unstable. For the heating of salt y water, situations are presented where the standing rolls, the standi ng patchwork quilt, and either the standing hexagons or the standing r egular triangles, may be stable.