Drag reduction on grooved cylinders in the critical Reynolds number regime

Experiments show that significant drag reductions may be realized for circular cylinders in cross-flow by using grooves, even at very shallow relative groove depths. It is demonstrated that the total groove area has a significant effect on reducing the critical Reynolds number, whether the area is increased through changing the groove shape, width, or depth. A strong correspondence to the minimum drag coefficient is also observed. (C) 2013 Elsevier Inc. All rights reserved.