Suppression of Vortex Shedding from a Circular Cylinder by using a Traveling Wave Wall

An experimental study was conducted to suppress the unsteady vortex shedding from a circular cylinder by using a traveling wave wall (TWW). The leeward surfaces of the circular cylinder model were replaced by wave surfaces, which can move to form symmetrical TWW when driven by a motor system. The propagation speed of the wave was adjustable by controlling the rotational speed of the motor. During the experiments, while the oncoming wind speed was fixed at U∞=9.1 m/s, the propagation speed of the TWW was adjusted to have the ratio between of the wave propagation speed and the oncoming wind speed varied from 0 (i.e., stationary case) to 0.167. It was found that, with the TWW control, the wake region behind the cylinder model was found to be shortened and the vortex shedding from the cylinder model was weakened greatly. The average drag force acting on the test model was also found to be reduced significantly. Two different mechanisms, i.e., “forced perturbation mechanism” and “resonant perturbation mechanism”, were found to play important roles for the TWW flow control.