Incorporating a semi-Lagrangian body-free-surface intersection point in a fully nonlinear potential flow model

This abstract presents our progress in the development of a fully nonlinear potential ow solver capable of modelling wave-structure and wave-bottom interactions. The numerical method is based on a finite difference method with a σ-transform in the vertical direction, as presented in Bingham and Zhang (2007), and boundary conditions are imposed in a robust way as described in Engsig-Karup et al. (2009). Wave-structure interaction is implemented using the Immersed Boundary Method (IBM) shown in Kontos et al. (2016), where the body boundary condition is satisfied by a Weighted Least Squares approximation, as described in Lindberg et al. (2014). The current work details the introduction of a semi-Lagrangian point tracking the body-free-surface intersection, which improves robustness and extends the capabilities of the solver to increasingly nonlinear wave-structure interaction. The accuracy and convergence of the scheme are validated by comparison with the second-order wave generation theory of Schäffer (1996).