Effect of a double wavy geometric disturbance on forced convection heat transfer at a subcritical Reynolds number

The present study initially considered the double wavy (DW) shape as the geometric disturbance to control fluid flow and the heat transfer. The large eddy simulation (LES) was performed to solve the filtered momentum and energy equations at the subcritical Reynolds number of 3000 and the Prandtl number of 0.7. In order to evaluate the effect of DW geometry on the force coefficients and the heat transfer, the smooth (CY), and symmetric wavy (SW) and asymmetric wavy (ASW) cylinders are considered for the purpose of the comparison. The DW cylinder achieved the smallest mean drag and the largest suppression of the lift fluctuation among the different geometric disturbances. The Nusselt number of the DW cylinder has the smallest mean and fluctuation values. The spanwise local Nusselt number is strongly correlated to the geometric disturbance, which is consistent with the SW and ASW cylinders. The DW cylinder provided smaller spanwise local Nusselt number over the span than the SW and ASW cylinders. The DW cylinder attenuates the heat transfer in comparison with the circular cylinder. The wake modification by the DW cylinder associates to the attenuation of the heat transfer. (C) 2019 Elsevier Ltd. All rights reserved.