Hydrodynamic performance of arc-shaped breakwater: Role of geometry and obliquity

This study investigates the hydrodynamic performance of arc-shaped breakwater (ASBW) under wave diffraction using the advanced non-hydrostatic shallow water model REEF3D::SFLOW. The model is validated against published results, confirming its ability to capture wave-breakwater interactions. Simulations are carried out for various arc opening angles (αa = 60°, 90°, 120°, 180°, and 270°) and wave incident angles (β = 0°, 15°, 30°, 45°, and 60°), revealing their influence on wave propagation, velocity distribution, and vorticity evolution behind the breakwater. Results indicate that the opening angle significantly affects wave attenuation and flow circulation, with wider arcs promoting more effective energy spreading and reducing transmitted wave energy. Detailed vorticity analysis highlights the development of dynamic vortices in the leeward region, with vortex strength, vortex radius, and trajectory highly sensitive to breakwater geometry and wave incidence. Increasing the wave obliquity alters diffraction patterns, shifts wave energy away from the arc center, reduces the sheltered zone, and generates asymmetries in wave runup and flow motion. The effect of relative wave height (H/d) is further examined, with higher values intensifying runup and transmitted wave energy. These findings offer new insight into energy dissipation and vortex behavior behind ASBW, supporting their optimization in coastal protection design.