Numerical study of three-dimensional flows around two identical square cylinders in staggered arrangements

With the aim to understand air pollutant dispersion among high-density, high-rise buildings, this paper presents the numerical results of three-dimensional flows around two identical square cylinders (TISCs) in staggered arrangements at a Reynolds number of 250 and zero incident angle when the angle between the incoming velocity vector and the line connecting the centers of the cylinders is 45°. The dependence of the drag and lift, their root mean square values, and the Strouhal number on the horizontal spacing have been evaluated. It was found that the correlation coefficients between the drag and lift of the upstream square cylinder (SC-I) were close to unity, with those for the downstream square cylinder (SC-II) exhibiting a wavy form along the spanwise direction. The wavelength and the magnitude are closely related to the cylinder spacing. Secondary vortex coherent structures as well as the primary vortex structures were reported and discussed.