Numerical Study on Flow around Four Square-Arranged Cylinders at Low Reynolds Numbers

In this paper, numerical simulations of flow past four square-arranged cylinders are carried out at different spacing ratios (1.5 <= L/D <= 5.0; L is the center to center distance; D is the cylinder diameter) and Reynolds numbers (100 <= Re <= 1000). The effects of spacing ratio and Reynolds number on the wake flow characteristics are investigated, such as the instantaneous vorticity contours, force coefficients, and vortex shedding frequencies. The results show that the flow characteristics behind the four-cylinder cases are significantly affected by the spacing ratios and Reynolds numbers. At the same spacing ratio, the transformation of flow pattern is advanced quickly with increasing of Reynolds numbers, the values of force coefficients are correspondingly fluctuated with large amplitude, and the vortex shedding frequency is increased significantly with Re.