Effect of Buoyancy on Turbulent Mixed Convection Flow Through Vertical and Horizontal Channels

Abstract

The effect of buoyancy on turbulent mixed convection flow through vertical and horizontal channels has been numerically studied. Turbulence is modeled by Reynolds averaged Navier - Stokes equations (RANS) with standard k - epsilon turbulence model. The present analysis is valid when the buoyancy force effects are small compared with the forced convection effects. The mixed convection flow problem is formulated by two dimensional unsteady incompressible flow with the buoyancy term modeled by Boussinesq approximation. The governing equations are solved by high accuracy compact finite difference schemes with four stage Runge-Kutta method for time integration. Results are reported for Reynolds number of 6000 with Richardson number varied from 0 to 0.5. The velocity, temperature profiles and average Nusselt number values are presented. The buoyancy shows significant effect on the flow and heat transfer characteristics in vertical channel in comparison with the horizontal channel. The effects of heated plate velocity relative to fluid velocity in a channel are reported. The present results are matching well with the experimental results available in the literature.