Slender rectangular obstacles are widely used in bridge decks, high-rise buildings, and hydraulic gates and valves, yet they are prone to wake instabilities and flow-induced vibrations. Corner modifications are known to effectively mitigate flow dynamics and flow-induced responses for square or elongated obstacles in smooth inflow, while their influence on slender obstacles under unsteady inflow conditions remains poorly understood. This study employs large eddy simulation coupled with the volume of fluid method to investigate the impact of rounded, chamfered, cut, and opening corners on the flow structures and hydrodynamic forces of a slender rectangular obstacle. Under unsteady inflow, corner modifications significantly reshape the flow around the slender obstacle by shifting separation point downstream, altering bottom-edge flow structures, and suppressing large-scale wake vortex formation, turbulence fluctuations and Reynolds stresses near the channel bottom increase, with turbulent kinetic energy rising by up to 43%. Vortex shedding from the bottom edge exhibits a multi-frequency pattern without a dominant peak, rounded corners most effectively accelerate the vortex shedding process. Corner modifications also modify the surface pressure distribution, lowering mean pressure on the front and bottom surfaces while producing sharp pressure jumps near the bottom edge. Mean and fluctuating drag coefficients decrease by 30.8% and 11.2% for the rounded corner model. Moreover, corner radius ratio R+ ≥ 0.2 decreases wake vortex size and coherent structure energy. These findings provide quantitative insights for optimizing corner design and flow-control strategies for slender bluff bodies.
Liu et al. (Thu,) studied this question.