A disturbance-sensitive Reynolds number range of the flow past a circular cylinder

The change by an order of magnitude of the oscillating properties of the flow past a circular cylinder in the Reynolds number range 2*10 3 to 5*10 4 is demonstrated experimentally. It is shown that in this range these properties are highly susceptible to small disturbances of the frequency of the transition waves which precede turbulence in the shear layers just downstream of the cylinder. It is suggested that this susceptibility is responsible for the different lift coefficient values measured by various workers. The effect of disturbances on the mean flow properties is also described. The frequency-determining mechanism and the characteristic length of the oscillating flow are discussed.