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A three-dimensional double-diffusive natural convection with opposing buoyancy effects in a cubic enclosure fi lled with fl uid saturated porous media is studied numerically using the boundary element method (BEM). The mathematical model is based on the space-averaged Navier-Stokes equations, which are coupled with the energy and species equations. The simulation of coupled laminar viscous fl ow, heat and solute transfer is performed using a combination of single-domain BEM and subdomain BEM, which solves the velocity-vorticity formulation of governing equations. The numerical simulations for a case of negative values of buoyancy coeffi cient are presented, focusing on the situations where the fl ow fi eld becomes three-dimensional. The results are analyzed in terms of the average heat and mass transfer at the walls of the enclosure. When possible, the results are compared with previous existing numerical data published in literature.

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A numerical study of double-diffusive natural convection in porous media using the Boundary Element Method is presented. The studied configuration is a horizontal layer filled with fluid saturated porous media, where different temperature and concentration values are applied on the horizontal walls, while the vertical walls are adiabatic and impermeable. Transport phenomena in porous media are described with the use of modified Navier-Stokes equations in the form of conservation laws for mass, momentum, energy and species. The results for different governing parameters (Rayleigh number, Darcy number, buoyancy ratio and Lewis number) are presented and compared with those in published studies.