Based on these studies it is known that vortex shedding in the sphere wake occurs for Reynolds numbers greater than about300. As the Reynolds number is increased beyond this value the vortex shedding process goes through a series of bifurcations which successively increase its complexity.
One characteristic feature of vortex shedding from cylinders is that every shedding cycle involves the formation of two counter-rotating vortices. As a result of this, the lift oscillates at the shedding frequency whereas the drag oscillates at twice the shedding frequency. Thus the cylinder wake exhibits a strong superharmonic component. In contrast vortex shedding from a sphere at low Reynolds numbers involves the formation of one vortex loop per shedding cycle and thus a significant superharmonic component does not exist. This difference between the two wakes is expected to result in a markedly different response to flow perturbations.