Numerical simulation of the entire fluid-structure interaction process of ship structures subjected to underwater explosion

When subjected to an underwater explosion, a ship may suffer severe structural damage and subsequent cabin flooding. This process is highly nonlinear, involving complex free-surface flows, structural fracture, and transient fluid-structure interactions. In this study, a fully meshless numerical framework is developed to simulate the entire fluid-structure interaction process of ship structures subjected to underwater explosion. This framework enables integrated simulation of the entire fluid-structure interaction (FSI) process from structure damage to cabin flooding. The fluid domain is modeled using a strongly compressible Riemann-SPH formulation during the explosive damage phase and a weakly compressible SPH model during the cabin flooding phase. Structural dynamics are resolved using the reproducing kernel particle method (RKPM), accounting for elastoplastic damage and crack propagation. At the fluid-structure interface, the normal flux method is employed to ensure compatibility in motion and dynamic conditions. The accuracy of the proposed framework is validated through comparisons with experimental results of underwater explosion-induced structural damage and cabin flooding, respectively. Furthermore, the entire process of structural damage and cabin flooding following an underwater contact explosion on a large-scale ship is successfully simulated. These results demonstrate the effectiveness of the established numerical framework in predicting the full sequence of events in underwater explosions.