STABILIZATION OF TRAPPED VORTICES BY ALTERNATING BLOWING SUCTION

Motion of a free point vortex near a circular cylinder in a uniform oncoming flow is considered. There is a point at which the point vortex velocity is zero. This stationary position is unstable. Introducing two periodic point sources of zero mean flow rate modifies the point vortex velocity field so that instead of the stationary position there is a periodic trajectory. The corresponding periodic motion of the vortex is found to be stable over a certain range of characteristics of periodic blowing/suction modeled with periodic sources. In particular, for stabilization the amplitude of the source flow rate oscillations must not exceed a certain limit. The results are believed to bear on the problem of enhancing lift at high angle of attack with the use of trapped vortices. © 1995 American Institute of Physics.