Cooperating Double Diffusion Natural Convection in a Square Enclosure with Partially Active Vertical Wall

摘要

Steady, laminar, double diffusion natural convection flow in a square enclosure with partially active vertical wall is considered. The enclosure is filled with a binary fluid and subjected to horizontal temperature and concentration gradients. The flow is driven by cooperating thermal and solutal buoyancies. Finite volume method is used to solve the dimensionless governing equations. The physical problem depends on five parameters: thermal Rayleigh number (Ra_t = 10~3-10~6), Prandtl number (Pr = 7), Schmidt number (Sc = 240), buoyancy forces ratio (N = 1) and the aspect ratio of the enclosure (A = 1). The active location takes three positions in the left wall: top (T), middle (M) and bottom (B). The main focus of the study is on examining the effect of Rayleigh number on fluid flow and heat and mass transfer rates. The results including the streamlines, isotherm and iso-concentration patterns, flow velocity and the average Nusselt and Sherwood numbers for different values of Ra_t. The obtained results show that the increase of Ra_t leads to enhance heat and mass transfer rates. The fluid particles move with greater velocity for higher thermal Rayleigh number. Also by moving the active location from the top to the bottom on the left vertical wall, convection and heat and mass transfer rates are more important in case (B). Furthermore for high Rayleigh number (Ra_t = 10~6), Convection mechanism in (T) case is principally in the top of the enclosure, whereas in the remaining cases it covers the entire enclosure.