Research on characteristics of deep-sea implosion based on Eulerian finite element method

Abstract

Marine structures operating in the deep-sea, such as submersibles and photomultiplier tubes, bear enormous hydrostatic pressure of deep-sea, which may cause structural damage and implosion. And a pressure wave will emit from the collapse of the cavity and pose a threat to nearby structures. On the basis of the Eulerian finite element method, the numerical model of multiphase flow for deep-sea implosion is established in this paper. The numerical method is verified by comparing the results with those from Keller equation and literature. The physical process under the spherical simplification is firstly analyzed in our work. The basic phenomena are studied, and the pressure changes under different distances and Mach numbers are given. Subsequently, the basic physical process and pressure distribution under cylindrical simplification are introduced. Then, the bubble evolutions under different Mach numbers and initial aspect ratios are given. In the early stage of bubble movement, a rarefaction wave will radiate to the surrounding. The multi-peak phenomenon will occur in the cylindrical model because of the bubble sides breakage and the bubble pulsation. Finally, asymmetric three-dimensional cylindrical bubble implosion near the solid wall with different standoff distances are present in this paper, where the typical oblique jet is observed and analyzed.