A physical wave maker system is established to generate the undular bores by superimposing successive solitary waves on the surge wave. The successive solitary waves are generated by the long-stroke piston wavemaker, and the surge wave is generated by a special valve-pump system. The valve-pump system is proved to produce the surge wave precisely and delicately. The superimposition appears that the solitary waves ride on the surge wave. The surge wave acts as the deeper water for the solitary wave to propagate, which affects the amplitude of solitary waves. In the present study, two successive solitary waves can be generated and superimposed on the surge wave, and the experimental data show good repeatability. A profile of the undular bores simulated by numerical computation is well reproduced in the basin.
Tsunami is one of the devastating natural hazards, which may cause thousands of fatalities and millions of property loss. Many numerical studies (Behrens and Dias, 2015) on the tsunami have frequently been reported in recent years, which greatly contribute to the understanding on the propagation mechanism of the tsunami and protection to the coastal structures. However, the computational cost and the complex topographies hinder the numerical simulation especially in the modelling of offshore and onshore processes. The physical model experiment is a good choice to study the mechanism of tsunamis in this region, such as the evolution and propagation with the sediment transport, and the inundation and the impact on the onshore structures.
The first question of the physical experiment for tsunami problem is how to generate the tsunami-like wave in the laboratory. As a simplification, the solitary wave generated by the wavemaker is widely used to mimic tsunami wave. Concerning the generation of solitary wave, Goring (1978) specified the movement of wavemaker plate to generate solitary waves, which was advanced by Malek-Mohammadi and Testik (2010). They took into account the unsteady nature of the solitary wave generation process. Xuan et al. (2013) studied the generation of two successive solitary waves of different amplitude. Although the piston-type wavemaker is doubted to satisfy the wavelengths and periods of the tsunami and the stable trough-led wave shape, many valuable achievements are still obtained by this simplification.