Onset of the second wake: Dependence on the Reynolds number

The second wake transition occurs in the far wake of a bluff body. This transition destroys the Bénard–von Kármán vortex street originating in the near wake and produces a secondary vortex street with a lower characteristic frequency. We characterize the onset of the second wake for Reynolds numbers 50<Re<800 in a nearly two-dimensional soap film flow. The dimensionless distance between the cylinder and the onset of the second wake decreases with Reynolds number consistently with Re−1/2 power law. Our two-dimensional far-wake numerical simulations are in good agreement with the experiment.