LES calculation for uniform flow past a rotationally oscillating cylinder

Two- and three-dimensional computations of flow past a rotationally oscillating cylinder are carried out at Re=150 and 1.5 x 10(4), respectively, to study the effectiveness of drag reduction through rotary oscillation of a cylinder. The turbulent wake is modeled by an LES technique. Two forcing amplitudes Omega = 0.5 and 2 with a wide range of forcing frequency f(e) are considered. The mean drag has a sharp increase during the lock-on range, and then decreases continuously to a minimum value. Up to 57% of drag reduction is achieved at Re = 1.5 x 10(4). As the forcing frequency further increases, the effect of cylinder oscillation diminishes and the mean drag approaches the value of flow past a stationary cylinder. Several different wake patterns, due to the variation of forcing frequency f(e), are observed by computational streaklines. (C) 2013 Elsevier Ltd. All rights reserved.