Implementation of Open Boundaries within a Two-Way Coupled SPH Model to Simulate Nonlinear Wave–Structure Interactions

A two-way coupling between the Smoothed Particle Hydrodynamics (SPH) solver DualSPHysics and the Fully Nonlinear Potential Flow solver OceanWave3D is presented. At the coupling interfaces within the SPH numerical domain, an open boundary formulation is applied. An inlet and outlet zone are filled with buffer particles. At the inlet, horizontal orbital velocities and surface elevations calculated using OceanWave3D are imposed on the buffer particles. At the outlet, horizontal orbital velocities are imposed, but the surface elevation is extrapolated from the fluid domain. Velocity corrections are applied to avoid unwanted reflections in the SPH fluid domain. The SPH surface elevation is coupled back to OceanWave3D, where the originally calculated free surface is overwritten. The coupling methodology is validated using a 2D test case of a floating box. Additionally, a 3D proof of concept is shown where overtopping waves are acting on a heaving cylinder. The two-way coupled model (exchange of information in two directions between the coupled models) has proven to be capable of simulating wave propagation and wave–structure interaction problems with an acceptable accuracy with error values remaining below the smoothing length h S P H .