Numerical simulation of flow around rectangular cylinders

We recently reported the experimental results of lift and drag forces, base pressure and Strouhal number of rectangular cylinders against Reynolds numbers and the side ratios of a model, measured in a wind tunnel and found the interesting fluid-characteristics and phenomena of flow. Then, we have calculated flows around rectangular cylinders in the range of low Reynolds numbers of 150 to 800 by a finite difference method (FDM) and flows at high Reynolds numbers by a discrete vortex method (DVM), to gain a better insight into the detailed flow characteristics. The results simulated by FDM successfully indicate the existence of the critical range of Reynolds number where the value of Strouhal number changes, accompanied with a drastic change of flow pattern. At high Reynolds numbers, we have computed flows around rectangular cylinders with different side ratios from 0.6 to 8 by DVM and succeeded in a simulation of the phenomenon that the value of Strouhal number abruptly changes when the side ratio of a model is 2.8 or 6, as the critical value. The computed results of flow pattern, base pressure, drag force and Strouhal number show a good agreement with the experimental ones.