Numerical investigation on the amplitude and mechanics of internal solitary waves generated by the gravity collapse method

The gravity collapse method is a commonly used approach to generate internal solitary waves (ISWs) in experimental or numerical tanks. Presently, the correlation between the wave-making parameters and the amplitude of the ISW produced via this approach is not well understood. The research presents a suggested amplitude expression that is derived from direct numerical simulations, dimensional analysis, and restricted linear regression. To our best knowledge, the expression is first presented in this paper and can be utilized as a useful tool to produce ISW with a specific amplitude. While the formula is often effective in predicting the ISW amplitude, it exhibits a slight inaccuracy in situations where the initial level difference is small and the collapse region is long. This is because the initial potential energy of the collapse region is not fully transformed into ISW energy. Furthermore, this research illustrates the mechanics of the collapse process and concludes that the near-bed horizontal velocities and transport properties induced by large-amplitude ISWs are inherent characteristics rather than being caused by the unstable process of wave generation.