Numerical Investigation of Extreme Wave Diffraction on Porous Pile Cone Breakwaters

Abstract Extreme wave events pose significant challenges to the operational safety and structural integrity of coastal infrastructure such as harbors. Porous pile cone breakwaters (PoPiCos) offer a promising solution for attenuating extreme waves and protecting harbor basins. This study investigates the influence of PoPiCo design parameters on the diffraction patterns and dissipation of extreme waves using a numerical modeling approach based on the Smoothed Particle Hydrodynamics (SPH) method implemented in DualSPHysics. Numerical simulations are performed on a 124.5m x 50m x 13.0m harbor basin model with a set of 6.5 m long PoPiCo installed as a protective barrier. Three regular wave scenarios with varying heights (1.74 m, 2.0 m, 2.4 m) and periods (6.51 s, 7.0 s, 5.0 s) are considered to assess the performance of PoPiCo under different extreme wave conditions. The simulation results reveal the effectiveness of PoPiCo in reducing wave energy, as evidenced by the obtained diffraction coefficients ranging from 0.42 to 1.11. The lowest diffraction coefficients (Kd) around 0.42-0.45 indicate that PoPiCo can dampen over 55% of the incident wave energy in the protected zone behind the structure. The ratio of breakwater gap width (B) to wavelength (L) is found to influence the diffraction characteristics and the extent of the protected zone. Increasing the B/L ratio from 0.66 to 0.86 results in more complex diffraction patterns and wider energy distribution behind PoPiCo. These findings highlight the importance of optimizing the PoPiCo design based on the B/L ratio to achieve effective wave attenuation and harbor protection. The study demonstrates the potential of PoPiCo as an economical and efficient alternative for safeguarding harbor basins against extreme wave threats.