Investigation on strong nonlinear interactions between underwater explosion and water surface based on compressible multiphase flow with phase transition.

The strong nonlinear interactions between underwater explosion and water surface were numerically investigated using a phase transition model based on a four-equation system, which can deal with the complex deformable interface among different phases, including water, air, explosion bubble, and cavitation. The numerical method is verified by comparing the numerical results with experimental results, and good agreements are found. This study considers an ideal sine wave for simulating the shape of water surface. Two examples of different detonation depths of charge are investigated. In each example, the first case is the basic simulation without surface wave, and the other three cases are the simulations with sine waves of different wavelengths. Unique characteristics of the interactions, such as shock wave propagation, explosion bubble expansion, and the generation, development, and collapse of cavitation, are observed in the numerical simulations. By capturing the detailed density and pressure contours during the interaction process, we can better understand the underlying mechanisms of the explosion bubble, cavitation, and surface waves. These numerical results demonstrate that geometric nonlinearity impacts cavitation evolution and the explosion bubble movement mechanism. Additionally, the secondary cavitation phenomenon has been found in the cases without surface wave, and its fundamental physical mechanism is presented in detail. The present results can expand the existing database of multiphase flow in the underwater explosion and provide an insight into the strong nonlinear interaction between the underwater explosion and water surface. [ABSTRACT FROM AUTHOR]