The object of this review is to investigate a physical mechanism for destabilization and disintegration of structure of coherent vortices which occur in many practical flows such as the horseshoe vortices which form at the junction of an appendage on a body in motion, and the coherent streamwise vortices in a turbulent shear layer. The vortices in these flows represent a significant drain in energy and have considerable bearing on the fluid forces exerted on the associated body or system; the vortices induce structural vibrations, contribute to flow noise, generate excess flow drag and in the case of the vortex pair in the wake of a large aircraft present significant hazard during landing to other aircrafts taking off from busy airports. A common feature of these flows is that the vortices persist either in an imposed weak strain or shear, one of the effects of which is to distort the shape of the core structure of the vortices. Available experimental or numerically simulated results suggest that imposing an external periodic pressure field or flow perturbation at certain frequencies on these flows has dramatic effects on the coherent vortices, inducing their suppression in some cases.
