Abstract
Direct numerical simulation of a fully-developed turbulent channel flow under control of a wave-like wall-normal body force is performed. An exponential decay of the wall-normal body force is assumed so that the body force acts in the regions near the walls only. Skin-friction drag reduction effect is confirmed while the net saving rate is negative and, if positive, subtle. The spanwise roller-like vortices are found to produce a negative Reynolds shear stress, which contributes to the drag reduction.
