Instability of the flow induced by an oscillating cylinder in a stratified fluid

Abstract

The stability of the secondary flow induced by a vertical circular cylinder performing transverse oscillations in a linearly stratified fluid at rest is investigated by means of flow visualization techniques. Compared with homogeneous fluids, the density gradient inhibits the onset of the three-dimensional instability. The instability appears as regularly spaced streaked flows along the cylinder axis and each streaked flow follows a wavy path in the horizontal plane in a certain range of amplitude and frequency of the oscillations.