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A numerical procedure that couples the Runge–Kutta discontinuous Galerkin method (RKDG), the boundary element method (BEM) and the finite element method (FEM) is developed to study the dynamics of an underwater explosion bubble near a sandwich structure efficiently and accurately. The numerical approach is validated by a near-field underwater explosion experiment. The numerical predicted bubble shape, cavitation and the free field pressure are in good agreement with the experimental results. The validated code is then used to determine the effects of the foam core strengths, the stand-off distances and the boundary condition of the back face sheet on the fluid response, the bubble behaviors, and the deformation of the sandwich structure. The results are beneficial for guiding the design of the protection structures. • Dynamics of an underwater explosion bubble near a sandwich structure is studied. • A numerical procedure that couples RKDG, BEM and FEM is developed. • Deformation of sandwich structures has significant effects on the bubble behaviors. [ABSTRACT FROM AUTHOR]

The dynamics of an underwater explosion bubble interacting with a moveable plate with basic characteristics of a sandwich structure are investigated numerically using boundary element method. The response of sandwich structures is assumed to be a moveable plate with a given velocity profile. The influence of the plate velocity profile, the standoff distance and the scale of the plate on the bubble behaviors are discussed. Within the scope of discussions, the bubble volume and period are a decreasing function of the maximum crushing velocity, the core compression, and the plate dimension, and an increasing function of the standoff distance. Three different regimes of bubble behaviors are distinguished: (1) jet directing towards the plate; (2) the bubble splitting into multiple bubbles or oscillating spherically without jet; (3) jet directing away from the plate. The results indicate that the sandwich plate which can provide larger deformation and larger maximum deformation velocity is beneficial for altering the jet direction to direct away from the plate. [ABSTRACT FROM AUTHOR]

A numerical solver coupling the Runge-Kutta discontinuous Galerkin method to the finite element method is proposed to solve the two-dimensional (2D) or axisymmetric response of deformable sandwich structures with metallic foam cores subjected to underwater explosion, in which the interactions of the gas bubble, the shock wave, the sandwich structure and cavitation are taken into account. The coupling method combines the advantages of the ghost fluid method (GFM) and the modified ghost fluid method (MGFM), where the Lagrangian interface velocity is directly set as the solution of the Riemann problem and the interface pressure and the fluid density are obtained by solving the Riemann problem (with the pre-known interface velocity). The obtained interface pressure then serves as the boundary condition to the Lagrangian domain. For the Eulerian domain, the remaining procedure is similar to the MGFM. The method proposed in this paper is material independent in simulating the fluid-structure interaction which is its major advantage compared with the original MGFM. The method is successfully validated by using analytical, numerical, and experimental results. [ABSTRACT FROM AUTHOR]