Hydroelastic response of a submerged structure to an underwater explosion

The use of composite structures in offshore engineering has revamped the problem of Fluid Structure Interaction (FSI) during underwater blasts because they enhance the FSI effect and increase the shock resistance of underwater structures. The practical applications of these materials range from warfare to offshore infrastructures and to the deep sea fuel transfer installations ([1],[2]). Nonetheless, the techniques that are usually applied to study the FSI rarely make use of the true coupling between the fluid dynamic problem and the structural one. Most frequently, the hydrodynamic-pressure approximation proposed by Taylor [3] for plates interacting with ex-plosion waves is included in the structural response ([2], [4]). This takes into account the reflected wave pressure and the damping effect due to the absorption of energy from the structure, but it is still a simplified approach. Only for air explosions, the complete coupling is actually modelled ([5],[6]) and only in 1D. Here, taking advantage of the Domain Decomposition strategy outlined in [7], a full 3D FSI investigation is carried out and the computed results highlight the effects of the structural response on the fluid. The differences with the simplified approach are outlined and more quantitative comparisons with available experimental data are underway and will be presented at the workshop. Description of the problem The FSI is studied using a 2-DOF structure placed in the path of an incoming spherical blast pressure wave generated by an explosion of a TNT charge as shown in the left panel of figure 1. The pressure wave, generated by the explosion, expand