Investigation of shock wave focusing in water in a logarithmic spiral duct, Part 1: Weak coupling

Shock focusing in water is a phenomenon that can occur during the impact of a shock wave generated by an underwater explosion onto any type of convergent marine structures. To predict the dynamic material response of the marine structure, it is important to understand the shock wave dynamics during the focusing event. In this paper, both experimental investigations and numerical studies of two-dimensional shock focusing in water are presented. Here, a convergent geometry given by a logarithmic spiral curve is used to focus the shock waves. In the experiments, the interaction between three types of materials and the shock wave in water is explored by using high-speed photography. Distinct features of such flows are unveiled. Three scenarios have been considered in simulations: a rigid structure where only the water-filled region is taken into account, a fluid-structure interaction problem in which the surrounding material responses are included, and an axisymmetric simulation to determine the three-dimensional effects.