Trapped vortex optimal control by suction and blowing at the wall

The flow due to a vortex trapped in a cavity is considered. The total circulation is constant and such that the Kutta condition is satisfied at the separation point when the vortex is on the equilibrium position S. If the vortex is slightly displaced from S it moves on closed trajectories. By using a classical variational technique, the suction/blowing intensity of the sinks/sources located on the flow boundary is determined so that the vortex is driven back to S. Examples of precomputed control and feed-back control in several flow configurations, including unstable equilibria and in the presence of random perturbations, are given.