A comparative study of parametric variation in forced convection and mixed convection flow in a channel with discrete heated modules at high Reynolds number

This mixed convection study compares the fluid and thermal behaviour of the developing flow in distributed heated modules along the lower wall of a rectangular channel at high Reynolds number in the presence (mixed) and absence (forced) of a buoyancy force generated due to the temperature difference between heated modules and the fluid near these modules. The time averaged mass, momentum and energy equations along with the k-ε equations for turbulent closure are solved. A special explicit method, MAC (marker and cell), is used to solve these governing equations. In this paper, a comparative study of the distribution of Nusselt number and pressure drop on the lower channel wall in forced and mixed convection cases is reported. The detailed analysis is presented through streamline plots, turbulent kinetic energy contours, pressure contours and temperature contours. It can be seen from this study that although the buoyancy force has a significant effect on the nature of the flow and thermal fields, the average Nusselt number and coefficient of pressure over each module is nearly the same for natural and mixed convection cases. The heat transfer coefficient and the pressure coefficient increase with module height but decrease with an increase in module length in both cases