Heat transfer and flow structure on periodically dimple–protrusion patterned walls in turbulent channel flow

Abstract In this study, heat transfer characteristics and flow structures over periodically dimple–protrusion patterned walls in a turbulent channel flow were systematically investigated using Detached Eddy Simulation method. The periodically patterned surface is applied to the bottom wall only in the test channel. It is found that larger depth/height induces higher friction factor and heat transfer. Furthermore, the highest Nusselt number is found to be located at the upstream portion of protrusion and the downstream portion of dimple. Additionally, the distributions of Nusselt number exhibit symmetrical features for the small depth/height configuration and asymmetric characteristics for the large depth/height configuration. The asymmetric distribution of localized Nusselt number at large depth/height is found to be closely linked to the asymmetric vortex inside the dimple.