Numerical simulation of the flow around two square cylinders using the lattice Boltzmann method

We present a numerical investigation on flow around two square cylinders in side-by-side, tandem, and staggered arrangements at Reynolds number Re=100 (which is based on the side length of the square cylinder). The dimensionless spacing between the two cylinders are T/D<5.0 and L/D<10.0 in the transverse and longitudinal directions, respectively. Numerical results reveal various flow patterns depending on the spacing, including the single bluff-body, flip-flopping, in-phase synchronized, and anti-phase synchronized patterns for the side-by-side arrangement, type-I and type-II patterns for the tandem arrangement, and nine complex flow patterns for the staggered arrangement. Moreover, these flow patterns can be divided into three categories: single bluff-body flow, small incidence angle flow, and large incidence angle flow. The flow structures, lift coefficient, drag coefficient, and Strouhal number (St) are presented to demonstrate the dependence of these parameters on the spacing, and the relationship between the flow pattern and lift and drag coefficients is also explored.