A two-phase flow model for wave–structure interaction using a virtual boundary force method

• Develop a two-phase flow numerical model to study wave–structure interaction.
• Derive a formulation based on the VBF method to calculate the total wave force.
• Use the VBF method to simulate a 3D breaking wave–structure interaction.

A three-dimensional two-phase flow model is developed to study wave interaction with structures by using a virtual boundary force (VBF) method. This model solves the Navier–Stokes equations for two-phase flows. The second-order accurate volume-of-fluid (VOF) method is used to track the free surface. In order to satisfy the no-slip condition on the rigid body surface, the virtual boundary forces are applied along the surface of the body in the computation. The model is first validated for wave interaction with a structure with the curved surface. This model is then used to simulate various types of two-dimensional and three-dimensional wave–structure interaction problems, i.e., solitary wave runup and rundown on a sloping beach, nonlinear wave transformation above a submerged breakwater, and wave diffraction around a large circular cylinder. The computational results compare well with available analytical solutions and experimental data. Lastly, as a demonstration, the three-dimensional wave breaking on a floating truncated circular cylinder is simulated and discussed.