Double diffusive convection in a cubic enclosure with opposing temperatureand concentration gradients

A three-dimensional numerical study has been performed to investigate doubl e-diffusive, natural convection in a cubic enclosure subject to opposing an d horizontal gradients of heat and solute. The flow is driven by buoyancy f orces due to temperature and solutal gradients. Constant temperature and co ncentration are imposed along the two vertical side walls of the cubic encl osure, while the remaining walls are impermeable and adiabatic. The numeric al 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. Nusse lt and Sherwood numbers are presented as functions of the governing paramet ers. Most of the published results approximate the problem as two dimension al. In the present results we indicate that the double diffusive flow in en closures 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].