Large-eddy simulation of flow mechanisms and wake dynamics around a wall-mounted square cylinder with façade ribs under turbulent inflow

Façade ribs are typically investigated as a modification strategy to improve flow control performance around a square cylinder. However, the effect of façade ribs on the flow control mechanisms and wake dynamics around a wall-mounted square cylinder is poorly understood. In this study, a large-eddy simulation is used to investigate the flow structures and forces around a wall-mounted square cylinder with various rib configurations. The results indicate that façade ribs significantly alter the mean flow, turbulent kinetic energy, and vortex structures, with continuous ribs having a more distinct effect. Vertical ribs generate localized corner vortices that mitigate turbulence and vortex shedding, whereas horizontal ribs reduce sidewall suction. Horizontal ribs have a negligible impact on drag, while vertical ribs reduce both mean drag and fluctuating lift, resulting in a 14.7% decrease in mean drag and a 35% decrease in fluctuating lift. The inflow turbulence intensity also affects rib performance, ribs elongate wake vortices under low turbulence intensity, whereas higher inflow turbulence intensity improves the rib-induced modulation of vortex dynamics and turbulent kinetic energy. The wall pressure fluctuations are most effectively mitigated under high inflow turbulence intensity, highlighting the stronger load-mitigation effect of the ribs, particularly the vertical ribs. These findings provide important insights into optimizing the flow control and mechanisms of wall-mounted square cylinders.