Vortex splitting and its consequences in the vortex street wake of cylinders at low Reynolds number

Based on the observation of vortex splitting in the laminar wake of thin flat plates placed parallel to the flow, an investigation on the consequences of such events for the von Kármán vortex street in the wake of circular cylinders was carried out. It was found that a ‘‘design break line’’ of vortex axes can lead to the decoupling of a wake flow from the always present disturbances deriving from the ends. The decoupling gives rise to parallel vortex shedding of a slightly higher frequency, instead of the oblique or slanted vortex shedding at a lower frequency usually observed.