This study investigates pressure distribution and horizontal wave force on a vertical breakwater and the variation of wave force with different incident period based on weakly compressible Smoothed Particle Hydrodynamics (WCSPH) and Flow-3D model, respectively. The numerical wave flume is established and the second-order waves are generated by a piston. Numerical calculation shows that the results of these two methods are in good agreement with experiments. In order to analyze the effect of pressure distribution and wave force with wave period, a series of numerical tests were carried out. Research results indicate that under the same incident wave height and water depth, as wave period increases, the pressure distribution and wave forces increase. Wave crest force basically increases linearly with the period. The increasing rate of the wave trough force gradually decreases. Under the same period and wave height, as the water depth increases, the crest force and trough force also increase.
Breakwaters are generally constructed for dissipation and reflection of incident wave energy in order to decrease the wave height to protect the coast against the erosion and to reduce the force acting on coastal structures. As wave period becomes longer, the wave loads on breakwater increases. Therefore, research on wave load with period is important significantly.
In coastal engineering, long period wave load on breakwater has attracted more and more attention. Long-period wave often occurs in the Arabian Sea (Amrutha et al. 2017), Indian Ocean (Tan et al. 2015) and so on. Many researches have been carried out on the wave force on the vertical breakwater. Sainflou (1928) proposed an analytical solution for pulsating wave loads. Minikin (1963) developed a formula to predict wave impact force. However, Minikin's formula is incorrect because wave force decreases with the incident wave length increasing (Allsop et al., 1996a). Fenton (1985) studied the wave pressure and forces on upright wall by potential theory. Goda (1974, 2000) developed a new formula to calculate the wave load on composite breakwater. This method has been widely used in coastal engineering and has been adopted in Japan and USA standards (Japan Standard 2009, EM 1110-2-1100 2011). However, these methods are based on potential theory and experimental data, and for some extreme cases, it may not be predictable very well.