Numerical Study on the Effects of Submerged Breakwater on Wave Overtopping

In order to protect beach or mud coastlines, submerged breakwaters are built in the world widely. When the submerged breakwater is designed, one important issue having to be analyzed is wave overtopping of coastlines or coastal preventing structures since the wave overtopping is very dangerous for people or structures on the potential coastal zones with probability of wave overtopping appearing. A 2-D numerical wave flume has been established based on Flow-3D software to investigate effects of incident wave parameters in front of the submerged breakwaters, slope of the beach and the submerged breakwaters themselves, respectively. The numerical wave flume has been verified by the theoretical data of wave equation and wave frequency spectrum of physical experiment. The computational results fitted well with the theoretical data. The calculated values of the overtopping are in good agreement with the physical model test values under the conditions of random wave. The verified model has been used to calculate the wave overtopping under the different wave height, wave period and slope of the beach. The results of numerical model test indicate that the wave overtopping without a submerged breakwater is much more than that with one for random wave approaching, which is similar as phenomena found in physical experiments. The relationship between wave overtopping and wave height, wave period, slope of the beach was discussed. And a new empirical formula to calculate the overtopping was fitted based on the method of dimensional analysis.