Numerical investigation of water entry problems using immersed boundary method

This paper presents a systematic numerical investigation on the water entry problems associated with dropping triangular wedges or ship sections by using an incompressible immersed boundary method (IBM). In the IBM, the solid bodies are treated as an additional phase and their motions are solved by a unified equation, similar to those governing the air and water flows; a level-set technique is used to identify the air-water interface and a projected Heaviside function is developed to identify the fluid-solid interface. For the purpose of comparison, corresponding numerical simulation, with or without considering the compressibility of the fluids, is also carried out by using OpenFOAM. All results are compared with the experimental data provided by the comparative study of ISOPE 2016. The results suggest that the unified equation in the IBM can well predict the motion of the dropping bodies; the IBM can capture the entrapped air and produce impact pressure, local and global forces which fairly agree with the experimental data.