STABILITY ANALYSIS OF DOUBLE-DIFFUSIVE CONVECTION IN A VERTICAL BRINKMAN POROUS ENCLOSURE

In this paper a linear stability analysis is presented for the problem of thermosolutal convection in a rectangular cell filled with a Brink man (sparsely packed) porous medium saturated by a binary fluid. Trans verse gradients of heat and solute are applied on the Vertical walls w hile the horizontal ones are adiabatic and impermeable. When the buoya ncy forces induced by the thermal and solutal effects are opposing eac h other and of equal intensity an equilibrium solution, corresponding to the rest state, is possible. The critical parameters for the onset of motion are determined using numerical procedures based on the Galer kin and finite element methods. The boundaries defining the regions of stationary and oscillatory instabilities are delineated. The Brinkman -extended momentum equation is used to model the flow in the porous me dium. Results for a pure viscous fluid and a Darcy (densely packed) po rous medium emerge from the present analysis as limiting cases. (C) 19 98 Elsevier Science Ltd.