Research on water entry problems of gas-structure-liquid coupling based on SPH method

The study on the dynamic response of deformable structure when it enters into the water is crucial for the stability and safety evaluation of structure. As a Lagrangian particle method, SPH (Smoothed Particle Hydrodynamics) has unique advantages in dealing with the free surface, multi-phase flow, and large deformation. So, this paper attempts to establish a unified SPH algorithm to study the coupling of deformable structure and multi-phase flow problem. Firstly, the strategies to eliminate the tensile instability in the gas phase, are put forward to ensure calculational stability. Moreover, the Riemann model between different materials is established to get a robust gas-structure-liquid contact algorithm, and the corresponding contact algorithm is presented. Finally, the water entry of an elastic wedge is simulated, and the elastic features of the water entry are revealed. The strategies to eliminate the tensile instability and the Riemann contact algorithm also demonstrate constructive effects. By comparing the results of the two-phase/three-phase water entry models, the effect of air on the dynamic response of the elastic wedge is analyzed. Moreover, the effects of the parameters such as elastic modulus, deadrise angle and air's dissipation are discussed to provide a reference for structural design in engineering.