Effect of Bluff Body Shape on the Growth Rate of Wake Instability

The laminar flow over bluff bodies having different shapes is numerically investigated. The different bluff bodies were created by either elongating or compressing the rear part of a circular cylinder. The growth of instability leads to the formation of the von Karman vortex street, which is studied using the Stuart-Landau equation. It was observed that the growth rate as well as the saturation amplitude of instability decreases linearly with the elongation of the circular cylinder. However, with the compression of the circular cylinder, there is little effect on the growth rate while an increase in the saturation amplitude can still be observed. The results indicate that a sufficiently elongated bluff body can suppress the formation of a von Karman vortex street at a given Reynolds number.