Numerical and experimental hydrodynamic assessment of internally partitioned thin porous breakwaters under regular and irregular sea states

Porous breakwaters play an important role in coastal protection by attenuating wave energy while allowing partial water permeation, thereby reducing wave reflection and structural loading. This study investigates the hydrodynamic performance of internally partitioned thin porous breakwater configurations using the dual boundary element method within the framework of linear wave theory. The quadratic pressure drop boundary condition is incorporated to better capture the effect of wave heights on energy dissipation and to represent pressure and velocity across the porous barriers. A series of structural configurations is numerically examined, revealing that for the triple-chambered configuration, the reflection coefficient (KR) is limited between 0.32 and 0.43, while the transmission coefficient (KT) is reduced by about 36%, and energy dissipation (KD) increases by about 20% compared with the base configuration over the tested range of k0h. Subsequently, it is chosen for experimental validation and parametric analysis due to its most balanced wave scattering behavior among the tested arrangements, with additional internal barriers adversely affecting energy dissipation. A porosity of ε=0.20 yields the highest energy dissipation (KD≈0.80) while maintaining controlled transmission (KT≈0.50) over the tested range. Further, the moderate chamber spacing and smaller barrier submergences provide the favorable hydrodynamic performance while maintaining material efficacy. Irregular-wave analysis shows that the proposed configuration maintains transmission (KT¯) below 0.50 and energy dissipation (KD¯) exceeding 60%, demonstrating its suitability for practical coastal protection and harbor applications.