Experimental study on hydrodynamic performance and structural forces of curved and vertical front face pile-supported permeable breakwaters

This paper presents an experimental study on the hydrodynamic characteristics and structural forces of pile-supported permeable breakwaters under regular wave conditions. The study evaluates three distinct configurations: one featuring a vertical superstructure, another with a permeable curved superstructure, and a third that combines a permeable curved superstructure incorporating a perforated diaphragm. Experiments were conducted under regulated wave conditions, focusing on pressures, forces, and hydrodynamic scattering coefficients associated with each structural form. Results from the experiments indicate that, under the conditions tested in this study, the curved permeable superstructure significantly reduces wave reflection coefficients and forces acting on critical elements. The curved permeable superstructure maintains reflection coefficients below 0.3 while ensuring low transmission coefficients. Moreover, the study explores dynamic water pressure on an inclined perforated plate and identifies an asymmetric double-peak phenomenon in the pressure time series, signifying the transition from regular waves to breaking waves. The critical wave steepness for the occurrence of double peaks was found to be lower than the breaking limit steepness. Filter analysis elucidates the generation mechanism and evolution pattern of this double-peak phenomenon, revealing the influence of relative water depth, with second-order harmonics dominating near the bottom and second- and third-order harmonics prevalent at the free water surface. This research contributes to the understanding of the hydrodynamic performance of pile-supported permeable breakwaters and underscores the benefits of the curved permeable superstructure design in reducing wave reflection and structural forces. The findings provide valuable insight for the further development and application of pile-supported breakwater structures.