Numerical study of turbulence effects on aerodynamic forces and flow field around a 4:1 rectangular cylinder using a virtual grid-generated turbulence method

Grid-generated turbulence is one of the most commonly used methods for simulating turbulent wind environments in wind engineering, and the conventional large eddy simulation approach that entity grids should be built and meshed in the computational domain for grid-generated turbulence suffers from prohibitive computational costs. To this end, a virtual grid-generated turbulence method that employs mathematical functions to precisely control inlet velocity distributions is proposed in this study. The influence of boundary conditions, incoming wind speed, kinematic viscosity, and grid size (width and spacing) on turbulence characteristics is systematically investigated. Furthermore, the aerodynamic forces and flow field mechanism of a 4:1 rectangular cylinder with different turbulence intensities are also comprehensively studied. The results indicate that the turbulence field generated by the proposed virtual grid-generated method exhibits excellent uniformity and isotropy. The effect of boundary conditions, incoming wind speed, and kinematic viscosity on turbulence field characteristics can be negligible. With the increase in turbulence intensity, vortex shedding from the rectangular cylinder is significantly suppressed, leading to reductions in the mean drag coefficient and the base suction coefficient but amplification in the fluctuating lift coefficient. This study not only provides a convenient and efficient LES turbulence generation method for structural wind-resistant analysis under turbulent conditions but also offers important theoretical support to estimate the aerodynamic performance of bluff bodies in complex wind fields.