Soret convection in a shallow porous cavity submitted to uniform fluxes of heat and mass

Soret effect on thermosolutal convection induced in a horizontal porous layer subject to constant heat and mass fluxes is investigated analytically and numerically. The thresholds for the onset of supercritical and subcritical convection are predicted explicitly as functions of the governing parameters. The present investigation showed the existence of different regions in the (N, Le) plane that correspond to different parallel flow regimes. The number and the locations of these regions depend on the parameter M, characterizing the Soret effect. For M <1, it is found that there exists a region in the (N, Le) plane where the parallel convective flow is not possible in the layer, regardless of the Rayleigh number considered. It is demonstrated that there exist combinations of the governing parameters for which the Soret effect imposes a reversal of the concentration gradient in the horizontal direction. (C) 2004 Elsevier Science Ltd.