NUMERICAL INVESTIGATION OF WAVE OVERTOPPING THROUGH DOUBLE PARAPET SEAWALL UNDER IRREGULAR WAVES

Abstract

 A double parapet seawall is one of the countermeasures against inundation caused by wave overtopping and surge overflow due to storm surges. In order to evaluate the wave overtopping discharge of the double parapet seawall countermeasures, the authors have conducted hydraulic experiments and numerical simulations on irregular waves. The numerical results of wave overtopping discharge was underestimated by one order of magnitude compared to the experimental results. In this study, additional numerical simulations were conducted to clarify the causes of underestimation and to improve the accuracy of the overtopping simulations. The numerical results of the additional simulations show that the overtopping discharge is smaller because of the attenuation of the high-frequency component waves. Next, the effects of parameters such as the mesh size and the coefficient controlling the compression of the interface were examined. It was shown that attenuation of the wave height was reduced by setting the Courant number to 0.125. By setting the optimal parameters and turbulence model, the numerical results of the overtopping discharge were in good agreement with the estimated equation obtained from the experimental results.