Drag and heat transfer in turbulent channel flow over shallow 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 analyzed using DNS and compared with a flat channel. The effect of shifting the deepest point of the dimples in a turbulent channel flow on their drag and heat transfer performance are 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 also manipulated by the geometry changes. The flow impingement on the dimpled wall increases the drag; consequently, the power required to drive the flow is increased. A study is conducted to investigate the effect of the shift in the deepest point of circular dimples on its heat transfer performance while minimizing the drag increase.