Model for the transition in bluff body wakes

Abstract
The transition from a peroidic vortex street to a less ordered state of vortex shedding in the wake of elongated bluff bodies is investigated in the case of a ring. Experimental results characterizing this transition are presented. The complex Ginzburg-Landau model, which is known to accurately describe the periodic regime, is extended to the transition range, and its predictions are compared to the experimental findings. The good agreement allows interpretation of the instability of the periodic vortex shedding in terms of the Benjamin-Feir instability of a one-dimensional system of coupled nonlinear oscillators.