Impact of crownwall shape on wave forces and overtopping at vertical breakwater

Vertical breakwaters are widely used to protect harbors exposed to waves propagating in deep water conditions, where overtopping can significantly affect operability and safety. The geometry of the crownwall plays a key role in mitigating wave overtopping, yet it also influences the impulsive loads associated with confined-crest impacts (C-CI). This study investigates the dual hydraulic and structural behavior of different crownwall configurations under non-breaking wave conditions through numerical modeling. Two-dimensional simulations were performed with the IHFOAM solver in OpenFOAM, which solves the RANS equations with a k–ε turbulence model and a Volume of Fluid approach to capture the air–water interface. Four crownwall geometries were analyzed: recurved parapet, rectilinear parapet, recurved crownwall, and vertical parapet. Results show that impulsive forces develop only in geometries featuring an overhang. Among them, the recurved crownwall produced the highest impulsive loads due to progressive confinement of the uprushing water crest, while the recurved parapet exhibited a more balanced performance, with moderate impulsive forces and effective overtopping reduction. Conversely, the vertical parapet experienced quasi-static pressures without impulsive peaks. Overtopping analysis indicated that the overhang extension has a stronger influence than curvature alone, with the recurved crownwall achieving the greatest reduction in overtopping volumes. However, the hydraulic benefits are counterbalanced by higher impulsive loads. These findings emphasize the importance of integrating hydraulic efficiency and structural safety in the design of vertical breakwater crownwalls. Future work will involve experimental validation and assessment under irregular wave conditions.