ON NATURAL-CONVECTION IN VERTICAL POROUS ENCLOSURES DUE TO OPPOSING FLUXES OF HEAT AND MASS PRESCRIBED AT THE VERTICAL WALLS

A two-dimensional mathematical model based on Darcy's law with Boussin esq approximation has been used to study double-diffusive natural conv ection in a rectangular fluid-saturated vertical porous enclosure subj ect to apposing and horizontal gradients of heat and solute. Results a re presented for 50 less than or equal to R(c) less than or equal to 2 50, 0.01 less than or equal to N less than or equal to 10, 10 less tha n or equal to Le less than or equal to 40 and 1 less than or equal to A less than or equal to 10, where R(c), N, Le and A correspond to the solutal Rayleigh-Darcy number, inverse of buoyancy ratio, Lewis number and enclosure aspect ratio, respectively. The numerical integration o f the full problem reveals that for sufficiently large R(c), Le and A, there is a domain of N in which one obtains oscillating convection. O utside this domain, the solution approaches steady-state convection, f or which analytical solutions are developed and presented. The agreeme nt between the analytical and the numerical solutions is shown to be s atisfactory.