Drag reduction effect by opposition control in turbulent flow along a cylinder by means of direct numerical simulation

Abstract

Opposition controlled fully developed turbulent flows along a thin cylinder are performed by means of direct numerical simulations. An influence of cylinder curvature on the skin-friction drag reduction effect by the classical opposition control (i.e., the radial velocity control) is mainly investigated. The curvature of cylinder affects the statistics of the flow; however, the control effect in the small curvature case is similar to that in channel flow. For large curvature, the drag is reduced even though the detection plane is located away the wall surface. The reduction rates of the present cases are larger than those in the channel flow.