Development of a 3D Domain-Decomposition strategy for violent head-sea wave-vessel interactions: Challenges

This research activity represents an additional step toward a three-dimensional Domain-Decomposition strategy for violent wave-ship interaction involving water-on-deck and slamming phenomena. The focus is on FPSO ships and on head-sea waves and vessel without forward speed. The compound solver under development aims to couple a global 3D linear seakeeping solver with an inner 3D single-phase (water) Navier-Stokes (NS) method in a region containing the forward portion of the vessel. The NS solver is characterized by a Projection method with a finite-difference scheme on an Eulerian grid. The Level-Set (LS) technique is applied to step in time the free surface and combined with point markers to enforce adequately the body-boundary condition within a hybrid Eulerian-Lagrangian approach. This requires a much finer discretization than the computational grid around the body to preserve its geometrical details in time. As time goes on, the markers move in a Lagrangian fashion and then the LS function is estimated on the Eulerian grid by interpolation from the markers locations. Previous efforts have been documented for instance in Greco et al. (2009)) and Colicchio et al. (2010). Here some of the challenges and the possible solutions for the development of the inner 3D NS solver are discussed. The stress is on the boundary conditions