On Drag Reduction and Heat Transferin Turbulent Channel Flow over Circular Dimples: The Shift of the Deepest Point of Dimples

Abstract

In this study, the flow characteristics and enhanced heat transfer performance of circular dimples in a channel flow were numerically analysed and compared with a flat channel. The effect of shifting the deepest point of the dimples in turbulent flow on their drag and heat transfer performance are also discussed. The strength and extent of the induced recirculating flow is suppressed significantly when the deepest point is shifted downstream, enhancing the heat transfer performance of the dimpled wall. At the same time, the flow structure above the dimpled wall is manipulated by the geometry changes. The flow impingement on the dimpled wall increases drag; consequently, the power required to drive the flow is increased. A parametric study is conducted to optimize the shifting of the deepest point to maximize heat transfer performance while minimizing the drag increase.