Abstract
A feedback control technique of vortex shedding behind a circular cylinder is investigated through two- and three-dimensional numerical simulations. Periodic velocity excitation is applied from the cylinder surface to the separated shear flows with a time delay and feedback gain for the fluid velocity at a downstream sensor location. It is shown that the feedback excitation can suppress the vortex shedding considerably. However, the suppressing effect on the vortex shedding becomes lower if the time delay is fixed between the feedback excitation and the fluid velocity at the sensor location or the sensor is located downstream of the formation region of the vortices behind the cylinder. This is because the change of the vortex shedding frequency and the wavelength resulting from the suppression of the vortex shedding alters the phase delay between the vortex shedding and the feedback excitation.
