WALL EFFECTS FOR THE PULSATILE MIXED CONVECTIVE FLOW AND HEAT TRANSFER AROUND A SEMI-CIRCULAR CYLINDER

Abstract

Pulsatile mixed convection flow and heat transfer of Newtonian fluid around a semi-circular cylinder in cross-buoyancy is investigated numerically. Due to applicability of fluid having Prandtl number, Pr = 7, is chosen for present work. Simulations are performed in following range of control parameters: Re = 100, Pr =7, β = 5 and 50%, Ri = 0, 0.5 and 1, A = 0, 0.1, 0.3 and 0.6, and St = 0, 0.1, 1 and 2. In current work, 4 tests (upstream, downstream, grid and time test) are conducted in order to optimize the computational domain. The influence of the pulsation amplitude (A) and Strouhal number (St) on the kinetic study of streamlines and isotherm has been presented. On the other side, the effect of the pulsation component (A and St) on drag coefficient (CD) and average Nusselt number (Nu) is analyzed. Comparison of the above study has been done with the non-pulsatile flow (St = 0). Total drag coefficient (CD) is found increases with increasing Richardson number (Ri) at Re = 100 because the addition of extra buoyancy force into the flow. Total drag coefficient (CD) also increases with the increasing blockage ratio due to the fact that the sharpening of velocity gradient between the adiabatic channel walls and boundary layer of heated semi-circular cylinder. Average Nusselt number (Nu) increases with increasing Ri for all values of β studied. For Re = 100, Nu also increases with increase in β. The maximum augmentation of around 12 and 24% were obtained in Nu and CD respectively for the case of A = 0.6 and St = 1 (with respect to the non-pulsating flow i.e. St = 0).