WALL EFFECT ON HEAT TRANSFER PAST A CIRCULAR CYLINDER - A NUMERICAL STUDY

This paper describes a numerical study on the unsteady laminar flow of an incompressible Newtonian fluid past a circular cylinder near a plane boundary using vorticity - stream function formulation. Thompson, Thames, Mastin (TTM) method of generation of automatic boundary fitted co-ordinate generation system is used to construct the grids of the physical flow field. The vorticity-transport equation, stream function equation and energy equations are first non dimentionalized and then transformed to computational domain In this study, finite difference implicit method is used to solve the transformed governing equations. The solutions are carried out for Reynolds numbers in the range between 20 to150 and gap ratio G/D (ratio of gap to diameter) in the range between 0.3 and 1.0. The flow parameters such as vorticity, stream function, velocity and temperature are calculated by providing appropriate boundary conditions for the same for different Reynolds numbers and different gap ratios. With these flow parameters, effect of flow field on the heat transfer around the cylinder is investigated. Nusselt number around the cylinder and average Nusselt number are shown as the function of Reynolds number and gap ratio. From this study it is found that heat transfer increases with increase in Reynolds Number. Mean Nusselt number increases with decrease in gap ratio.