Wave-body interactions play an important role in many engineering fields, such as ship and ocean engineering. In this paper, a two-dimensional three-phase flow model for simulating wave-body interactions is developed. Besides the conventional two-phase flow model in which gas and liquid are solved, the solid body is considered as the third phase so that wave-body interactions are considered as three-phase problems. Local Mesh Refinement (LMR) grid is adopted to reduce the computational cost. Benchmark cases of water entry and exit of a circular cylinder, as well as the radiation of a box-type breakwater are used to validate the model. Acceptable agreements are obtained between the numerical results of current model and data from other sources.
As one of the most violent interactions between solid bodies and free surfaces, wave-body interactions play an important role in many engineering fields. Computational Fluid Dynamics (CFD) techniques are nowadays widely utilized to investigate the hydrodynamics of these problems. However, there are still many difficulties in numerical simulating wave-body interactions. A typical problem is how to track the body surface and enforce the boundary condition, especially when the body is not in stationary. Besides, computational cost is always a bottleneck in CFD.
For a body-fitted grid in which the grid is aligned with the body surface, the enforcement of boundary conditions is simple. While the tracking of the body could be complicated. Arbitrary Lagrangian Eulerian (ALE) method is widely utilized for this grid (Donea et al. (2004)). The grid follows the motion of the body with grid stretch or reconstruction to keep align with the body surface. The method would not be so stable when the motion of the body is large. For a large motion of a body, the over-set grid could be a better choice. While the conservation of the over-set grid is not easy to preserve (Ferziger & Perić (2002)).
The non-body-fitted methods based on a Cartesian grid are a good alternative. On a Cartesian grid, the solid body is considered as the third phase and the methods for capturing/tracking the interface in multiphase flow could be adopted. VOF method (Hu and Kashiwagi (2004), Ghasemi et al. (2014)) and Level-Set method (Yang and Stern (2009)) were used to capture the body. Usually, the Immersed Boundary (IB) method are adopted for the treatment of boundary conditions (Yang and Stern (2009)).