EFFECTS OF PARTIAL HEATING OF TOP ROTATING LID WITH AXIAL TEMPERATURE GRADIENT ON VORTEX BREAKDOWN IN CASE OF AXISYMMETRIC STRATIFIED LID DRIVEN SWIRLING FLOW

The present numerical simulation investigates the effects of partial heating on confined stratified swirling flow in a cylindrical cavity with a top rotating lid. The flow patterns and the heat transfer characteristics are numerically investigated under the Boussinesq assumptions. The inner region of the surface of top rotating lid of cylindrical cavity, with radius less than or equal to radius of the lid, is kept at a higher temperature as compared to the bottom stationary wall. The remaining outer region of the top rotating lid and the side wall are perfectly insulated. A systematic study has been carried out by varying radius of the hotter region of the top rotating lid. Steady state axisymmetric solutions are obtained in cylindrical regime with a fixed values of the governing parameters, the Reynolds number 1500, Richardson number 0.05 and Prandtl number 1.0 for a cavity of aspect ratio 1.8. The vortex breakdown size, numbers and position are found to be changing with increase in partial heating. Variation in magnitude of local as well as average Nusselt number in vicinity to top rotating lid are significantly influenced by increase in partial heating radius of top rotating lid. Also variations in coefficient of torque are studied.