LINEAR STABILITY ANALYSIS OF SEPARATED SHEAR FLOWS AROUND A CIRCULAR CYLINDER

Abstract

In order to investigate the instability of the separated shear flows around a circular cylinder, a series of linear stability analyses was carried out. The analyses confirmed that the fluctuation with the transition wave frequency is enhanced most efficiently in the separated shear layer. It is also found that the vortices induced by such fluctuation frequently merge in the separated shear layer due to the increase of their wave number and the decrease of their phase velocity. Furthermore, these strong vortices change the flow instability just behind the cylinder and then alter the characteristics of the Karman vortex-shedding.