球体垂直入水空泡内部流场特性的数值模拟研究

Based on the boundary data immersion method (BDIM) and the fluid-structure coupling algorithm for rigid body motions, a numerical program for the vertical water-entry of a sphere was developed. The accuracy and effectiveness of the numerical method were verified by comparison with the experimental results. Based on the analysis of the numerical calculation results, the cavity development and corresponding flow structures with different impact velocities during vertical water entry, as well as the development of the splash were obtained. Different vortex identification criteria were adopted to investigate the development of vortex structures. The results show that the impact velocity of the sphere has a significant effect on the closure of the splash, the cavity shape and the evolution of the flow structures inside the cavity. The Q criterion can identify the complex vortex structure more accurately, and the entry velocity of the sphere will affect the vortex intensity inside the cavity.