Double diffusive convection in a cubic enclosure with opposing temperature and concentration gradients

A three-dimensional numerical study has been performed to investigate double-diffusive, natural convection in a cubic enclosure subject to opposing and horizontal gradients of heat and solute. The flow is driven by buoyancy forces due to temperature and solutal gradients. Constant temperature and concentration are imposed along the two vertical side walls of the cubic enclosure, while the remaining walls are impermeable and adiabatic. The numerical simulations presented here span a wide range of thermal Rayleigh number (10.0 < Ra < 2x10(5)), buoyancy ratio (-2.0 < N < 0) and Lewis number (0.1 < Le < 150) to identify the different flow patterns and bifurcations. Nusselt and Sherwood numbers are presented as functions of the governing parameters. Most of the published results approximate the problem as two dimensional. In the present results we indicate that the double diffusive flow in enclosures with opposing buoyancy forces is strictly three dimensional for a certain range of parameters. (C) 2000 American Institute of Physics. [S1070-6631(00)01208-3].