Effects of dimple depth and Reynolds number on the turbulent heat transfer in a dimpled channel

摘要

A Large Eddy Simulation (LES) has been conducted for the flow and heat transfer in a dimpled channel. Two dimple depths of 0.2 and 0.3 times of dimple print diameter (=D) have been compared at the bulk Reynolds number of 20,000. Three Reynolds numbers of 5000, 10,000 and 20,000 have been studied, while the dimple depth is kept as 0.2 D. With the deeper dimple, the flow reattachment occurs father downstream inside the dimple, so that the heat transfer is not as effectively enhanced as the case with the shallow ones. At the low Reynolds number of 5000, the Nusselt number ratio is as high as those for the higher Reynolds number, although the value of heat transfer coefficient decreases because of the weak shear layer vortices.