水下爆炸会对舰船结构造成致命的毁伤，涉及激波传播、多介质与相变、非线性大变形、结构塑性损伤及瞬态流固耦合等核心问题。发展水下爆炸时域全过程流固耦合算法，探究水下爆炸对结构造成的毁伤机制，在学术与工程上都具有重大意义。本项目利用间断伽辽金(DG)方法善于处理激波问题的特点，发展拉格朗日(Lagrangian)框架下的DG算法，结合网格拓扑优化技术与空化模型，建立水下爆炸多相流Lagrangian-DG模型，对水下爆炸时域全过程进行精细化模拟，研究不同边界附近水下爆炸载荷特性、气泡运动特性及空化区域的发展规律；在此基础上，结合结构损伤动力学模型，提出水下爆炸双向流固耦合算法，研究水下爆炸气-液-固三相介质的强非线性耦合效应，精准预报水下爆炸载荷对结构造成的毁伤响应；最后，结合水下爆炸实验，探究水下爆炸载荷对结构造成的损伤机理，旨在为船舶与海洋工程水下爆炸领域的研究提供理论基础与技术支撑。

The underwater explosion (UNDEX) could cause serious damage to the warships. The physical process involves a series of key problems, such as shock wave, transitions between liquid and gaseous phases, large nonlinear deformation of gas-liquid interface, plastic deformation of structure, transient fluid-structure interaction (FSI) and so on. It’s significant both in academics and engineering to develop the UNDEX FSI numerical model in the whole time domain, and to further study the mechanism about damage characteristics of structure subjected to UNDEX. Due to the advantage of discontinuous Galerkin (DG) method in capturing discontinuous wave, this project develops the DG method in the Lagrangian frame to solve the compressible Euler equation. By combing with the mesh topology optimization technique and cavitation model, we establish the UNDEX multiphase Lagrangian-DG model, which can precisely simulate the whole process of UNDEX. The effects of boundary conditions on UNDEX load characteristics, non-spherical bubble characteristics and the dynamic growth of the cavitation zone are studied. Besides, by combing with the structural damage dynamic model, we propose the two-way FSI algorithm. Based on the FSI model, the strong nonlinear coupled effects between the gas-liquid-solid phases are investigated, and the dynamic responses of the structure subjected to UNDEX are predicted accurately. Finally, the developed Lagrangian-DG FSI model, together with the UNDEX experiments, are used to study the mechanism about damage characteristics of the structure subjected to the UNDEX loads in the whole physical process. This project aims to provide the theoretical basis and technical support to the UNDEX investigations in the naval architecture and ocean engineering.