Investigation of Coriolis Forces Effect of Flow Structure and Heat Transfer Distribution in a Rotating Dimpled Channel

Abstract

Large-eddy simulations are used to investigate Coriolis forces effect on flow structure and heat transfer in a rotating dimpled channel. Two geometries with two dimple depths are considered, δ=0.2 and 0.3 of channel height, for a wide range of rotation number, Rob=0.0–0.70, based on mean bulk velocity and channel height. It is found that the turbulent flow is destabilized near the trailing side and stabilized near the leading side, with secondary flow structures generated in the channel under the effect of Coriolis forces. Higher heat transfer levels are obtained at the trailing surface of the channel, especially in regions of flow reattachment and boundary layer regeneration at the dimple surface. Coriolis forces showed a stronger effect on the flow structure for the shallow dimple geometry (δ=0.2) compared with the deeper dimple where the growth and shrinkage of the flow recirculation zone in the dimple cavity with rotation were more pronounced than the deep dimple geometry (δ=0.3). Under the action of rotation, heat transfer augmentation increased by 57% for δ=0.2 and by 70% for δ=0.3 on the trailing side and dropped by 50% for δ=0.2 and by 45% for δ=0.3 on the leading side from that of the stationary case.