Experimental study of the wave-dissipating performance of a four-layer horizontal porous-plate breakwater

Abstract

This paper proposes a four-layer submerged horizontal porous plate breakwater to improve the wave-dissipation efficiency under a wide range of incident wave frequencies, especially long incident waves, and also discusses the design of the geometrical parameters, i.e., plate submergence and porosity. The breakwater performance was examined experimentally in a two-dimensional wave flume. The effects of the layer number, breakwater width, upper plate porosity, and incident wave height were compared. Increasing the layer number and breakwater width or reducing the upper plate porosity can be favorable to energy dissipation for long incident waves. A moderate alteration of the submerged depth of each layer shifts the proportion of energy reflected or transmitted but minimally affects the energy-dissipation performance. In addition, the incident wave height affects both energy dissipation and mass overtopping, and the combined effect is related to the incident wave frequency and steepness. Generally, the proposed four-layer breakwater demonstrates satisfactory performance under a wide range of incident wavelengths and has promising future applications in coastal engineering. An optimized design for the plate porosity and submergence can be expected to further improve the breakwater performance, and a detailed mechanism for non-linear wave interactions with the submerged horizontal porous plate warrants further study.