A new integrated finite volume–finite volume numerical model for wave-structure interactions

This paper presents a new integrated (hybrid) hydrodynamic numerical model which couples a finite volume-based fully nonlinear potential flow (FNPF) solver with an incompressible two-phase Navier-Stokes (NS) solver in OpenFOAM. The coupling procedure follows a domain (zonal) decomposition approach in which an overlapping relaxation zone is utilised to implement a weak (one-way) coupling. The method for transferring information is simple, and the coupling accurate. Indeed, given that both solvers have been developed in OpenFOAM and are finite volume-based, only a method to calculate the volume fraction from the free-surface elevation has to be implemented: the velocity and pressure are already calculated as part of the FNPF solution and can be transferred accordingly—simplifying things greatly and avoiding unwanted errors. In addition, existing advanced OpenFOAM functionalities are used for the required interpolation. The relaxation zone then also ensures the coupling process is stable through a smooth transition from the FNPF solution to the N-S solution, as well as by absorbing any reflected waves. The new model is then validated through a number of benchmark test cases involving wave propagation, transformation, and structure interaction. It is shown to produce accurate numerical solutions that agree well with existing theoretical results and experimental data