Numerical investigation of hydrodynamic characteristics around bridge piers under wind–wave–current conditions

This study presents a fully coupled computational fluids dynamics model to investigate the hydrodynamic characteristics around a bridge pier under combined wind–wave–current conditions. The numerical model, validated against Morison theory, accurately captures wave propagation and force generation. A series of 15 scenarios is simulated to identify the effects of wave height, wave period, current velocity, and wind speed. Key findings indicate that (i) peak wave forces increase quasi-linearly with wave height but saturate after incipient breaking; (ii) each 0.1 m/s increase in current velocity amplifies positive force peaks by approximately 3% and reduces negative peaks by about 2.9%; (iii) a critical wind-speed threshold (close to wave celerity) triggers a 19% surge in positive forces and an 8.9% decrease in negative forces; (iv) nonlinear coupling effects lead to a peak synergy coefficient of 1.23 under extreme conditions, demonstrating that linear superposition underestimates design loads by over 20%. The results emphasize the necessity of incorporating wind–wave–current coupling in reliability-based design practices for marine bridge piers to avoid underestimation.