Conjugate effects of shear-driven and buoyancy-induced flow of a reacting chemical in a lid-driven enclosure

The flow structures and heat transfer characteristics of the mixed convective flow of a chemical reactant in a lid-driven enclosure are investigated. Effect of the magnetic field is also considered. The walls of the enclosure are maintained at the surrounding temperature. Moreover, the top wall is assumed to move with a constant velocity resulting in shear-driven flow below it. The buoyancy-induced flow is caused by the heat released from the exothermic chemical reaction. High order compact finite difference technique combined with successive over relaxation (SOR) method is used to solve the problem. Numerical results reveal that the magnitude of stream function significantly increases with higher Grashof number (Gr) and Frank-Kamenetskii number (?), while it decreases with increasing Hartmann number (Ha) and Lewis number (Le). A remarkable finding is that when the Reynolds number (Re) is fixed at 20, single clockwise vortex is observed for Gr = 10(3), whereas two vortices of opposite strength occur for Gr = 10(4) and 10(5). On the other hand, when Gr = 10(5), two vortices are seen for Re = 30, but the single vortex is generated for Re = 300 and 10(3). The maximum temperature decreases owing to the increase of all parameters except for ?. Furthermore, the magnitude of heat transfer across the walls considerably decreases for larger Le and Re, whereas it substantially increases with higher ?.