Double-diffusive natural convection in a rectangular cavity with partially thermally active side walls

Double-diffusive natural convection in a rectangular cavity with partially thermally active side walls filled with air is studied numerically. The active part of the left side wall has a higher temperature and concentration than the right side one. The length of the thermally active part is equal to half of the cavity height. The top and bottom of the cavity and inactive part of the side walls are considered to be adiabatic and impermeable to mass transfer. Placement order of thermal active walls has significant effect on heat and mass transfer rate, to explore this effect and achieving the optimum rate inside the cavity, nine different relative positions of the active zones are considered. The non-dimensional forms of governing transport equations describing double-diffusive natural convection for laminar two-dimensional incompressible flow are functions of vorticity, temperature or energy, concentration and stream-function. Laminar regime is considered under steady state condition. The coupled differential equations are discretized by the finite difference method and are solved using the successive-over-relaxation (SOR) method. The results are obtained for different heating sections and different parameters such as aspect ratio, buoyancy ratio and Schmidt number. Also the heat and mass transfer rate in the cavity is measured in terms of the average Nusselt and Sherwood numbers.