Estimation of the transmission coefficients of wave height and period after smooth submerged breakwater using a non-hydrostatic wave model

Abstract

In the present study, new empirical formulas of wave transmission coefficients, including Kp for the mean wave period and Kt for the significant wave height, defined as the ratios between the transmitted and incident values of a smooth submerged breakwater, are proposed based on results simulated using the SWASH non-hydrostatic wave model. According to the analysis of the numerical results, both Kt and Kp are less than 1.0, and the transmitted peak period is close to the incident peak period in most cases. The reduction of wave height is mainly caused by energy loss due to wave breaking, and the reduction of the mean period is mainly caused by the generation of high-frequency harmonics after the submerged breakwater. Moreover, both Kt and Kp have good linear correlations with the relative submergences, and Kp has a good linear relationship with wave steepness. The relative crest width and slope have no significant effect on the transmission coefficient of the submerged breakwater compared with the effects of the relative submergences and wave steepness. Based on the factors mentioned above, new empirical formulas are formed. The coefficients of determination (RCor2) of Kt and Kp between measurements and values calculated using the new empirical formulas are 0.90 and 0.95, respectively, representing an improvement over the models of Van der Meer et al. (2003) and Carevic et al. (2013). The sensitivities of Kt and Kp to the variables in the empirical formulas are also investigated. According to the sensitivity analysis, a simplified formula of Kt is suggested based on the relative submergence and breaker parameter, and a simplified formula of Kp is proposed based on the relative submergence and wave steepness.