Optimization analysis of non-porous and porous trapezoidal submerged breakwaters for reducing wave transmission

초록

This study investigates the optimal design of trapezoidal submerged breakwaters to reduce frequency-averaged wave transmission coefficients under irregular wave conditions. A two-dimensional multi-domain frequencydomain boundary element method (MDFD-BEM), based on linear potential flow theory, was developed for hydrodynamic analysis. This method was integrated into an optimization framework employing a metaheuristic algorithm. Four configurations were analyzed: single and double arrangements of both non-porous and porous submerged breakwaters. The design variables included the height, side slopes, and top width of each breakwater, as well as the spacing between paired structures. Key findings indicate that wave transmission decreases exponentially with increasing breakwater height. An optimal ratio of top width and spacing to the incident peak wavelength was identified for reducing transmission. In two-breakwater configurations, the minimum transmission coefficients were achieved when the two breakwaters had nearly identical shapes and areas. Compared to single-breakwater cases, the total area approximately doubled, leading to reductions in wave transmission of approximately 17 % for non-porous and 45 % for porous configurations.

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