Optimization of Cross-sectional Design to Enhance the Efficiency of Submerged Breakwater for Reducing Mean Water Level behind Structure

Abstract

This study examines the optimal cross-sectional design of a submerged breakwater to enhance its efficiency in reducing the mean water level behind the structure. The objective is to achieve effective wave control and reduce the mean water level behind the structure to mitigate the damage caused by high waves at the coast. The numerical wave tank is employed to verify the validity and feasibility of the submerged structure by comparing its wave control characteristics and the hydraulic properties of the mean water level behind the structure with the results of existing hydraulic model experiments. The hydraulic characteristics are calculated from the computed free surface data using the wave reflection and transmission splitting method. The mean water level behind the structure is compared by nondimensionalizing the averaged free surface with the incident wave height. The important results of the examined optimal cross-sectional shape are as follows: An optimal cross-section is identified when it is larger than or equal to 1.8 of the incident wave height. Herein, the examined breakwater achieves a reduction of approximately 72% in the mean water level behind the structure and wave attenuation of at least 10%. Therefore, the submerged breakwater cross-sectional shape examined in this study can appropriately regulate the increase in the mean water level behind the structure while providing wave control.