Two-dimensional vortex shedding of a circular cylinder

The Strouhal–Reynolds number relationship for the two-dimensional (2-D) vortex shedding of a circular cylinder at low to medium Reynolds numbers (Re, ranging from 45 to 560) is investigated experimentally. Both horizontal and vertical soap film tunnels are used to set up a truly 2-D experiment. It is found that two separate 3-D instabilities of the natural wake at Re≅180 and 260 disappear. The Strouhal–Reynolds number curve is in good agreement with the 2-D computations of Barkley and Henderson [J. Fluid Mech. 322, 215 (1996)]. The 2-D asymptote of 0.2417 of Strouhal number is also approached.