PATTERN SELECTION IN DOUBLE-DIFFUSIVE FERRO-CONVECTION

Pattern formation due to double-diffusive convection in ferrofluids is investigated in the presence of an externally applied transverse magn etic field. The critical value of the Rayleigh number R for steady sta te bifurcation is found to be different from that for Hopf bifurcation in contrast to ordinary fluids where the two critical values are the same. The stability of steady state patterns-rolls, squares, and hexag ons-has been discussed. For magnetic fluids, the rolls are found to be structurally stable on the square lattice, whereas on the hexagon lat tice bifurcation may lead to either rolls or hexagons depending upon t he value of the nondimensional magnetic parameter M. (C) 1998 Academic Press.