Hysteresis at low Reynolds number: the onset of 2D vortex shedding

Abstract

Hysteresis has been observed in a study of the transition between laminar flow and vortex shedding in a quasi-two dimensional system. The system is a vertical, rapidly flowing soap film which is penetrated by a rod oriented perpendicular to the film plane. Our experiments show that the transition from laminar flow to a periodic Kármán vortex street can be hysteretic, i.e. vortices can survive at velocities lower than the velocity needed to generate them.

RevTeX file 4 pages + 5 (encapsulated postscript) figures. to appear in Phys.Rev.E, Rapid Communication