Experimental and numerical analysis of vortex shedding from elongated rectangular cylinders at low Reynolds numbers 200-10³

Experimental and numerical investigation on vortex shedding from elongated rectangular cylinders at low Reynolds numbers 200-10³ was performed in this paper. The experiment was made in a low speed wind tunnel, and the numerical analysis was based on the finite difference method applicable to the 2D Navier-Stokes equations. The side ratio of rectangular cylinders tested ranged from 3 to 16 in the experiment, and 3 to 10 in the numerical computation. Good agreement was obtained between experiment and numerical analysis of the Strouhal number. With increasing Reynolds number, transition was observed in the type of vortex shedding, i.e., from the Kármán type shedding to the impinging-shear-layer instability, where a single separated shear layer can be unstable in the presence of a sharp trailing edge corner. The transitional Reynolds number was roughly equal to 300.