Classification of flow regimes and interference mechanisms for three equilateral square cylinders at various wind angles

The wind direction angle is an important factor affecting the flow field and forces around square columns, substantially altering wake characteristics. Configurations with closer spacing exhibit greater sensitivity to wind direction changes than widely spaced arrangements. To investigate the influence of wind direction angle on the aerodynamic characteristics and surrounding flow field, this study examines three equilateral arranged square columns at a Reynolds number of 8.2×10⁶ and a spacing ratio of 2.5 under various wind direction angles. Three-dimensional numerical simulations are employed to analyze the effects of wind direction angle on the flow characteristics, surface pressure distribution, and force coefficients. According to the characteristics of wake under different wind directions, the three-square cylinder is divided into five different flow patterns. The vortex interaction mechanisms around each cylinder and the wake interference features are elucidated. The surface pressure coefficient, along-wind force coefficient, and across-wind force coefficient of each cylinder under different flow patterns are compared and analyzed. Notably, at wind direction angles of 0° and 180°, the flow field exhibits distinct patterns due to the differing number of upstream columns.