Dynamic Response of Floating Body Subjected to Underwater Explosion Bubble and Generated Waves with 2D Numerical Model

The low frequency load of an underwater explosion bubble and the generated waves can cause significant rigid motion of a ship that threaten its stability. In order to study the fluid-structure interaction qualitatively, a two-dimensional underwater explosion bubble dynamics model, based on the potential flow theory, is established with a double-vortex model for the doubly connected bubble dynamics simulation, and the bubble shows similar dynamics to that in 3-dimensional domain. A fully nonlinear fluid-structure interaction model is established considering the rigid motion of the floating body using the mode-decomposition method. Convergence test of the model is implemented by simulating the free rolling motion of a floating body in still water. Through the simulation of the interaction of the underwater explosion bubble, the generated waves and the floating body based on the presented model, the influences of the buoyancy parameter and the distance parameter are discussed. It is found that the impact loads on floating body caused by underwater explosion bubble near the free surface can be divided into 3 components: bubble pulsation, jet impact, and slamming load of the generated waves, and the intensity of each component changes nonlinearly with the buoyance parameter. The bubble pulsation load decays with the increase in the horizontal distance. However, the impact load from the generated waves is not monotonous to distance. It increases with the distance within a particular distance threshold, but decays thereafter.