The SWENSE (Spectral Wave Explicit Navier-Stokes Equations) approach has been developed since 2003 by the Hydrodynamics & Ocean Engineering (HOE) group of Ecole Centrale de Nantes (ECN). This approach allows the simulation of wave-structure interactions in viscous flow in a very efficient way, by combining the description of undisturbed incident waves by a nonlinear spectral scheme based on potential flow theory and the computation of the nonlinear viscous diffracted flow using the free surface Reynolds Averaged Navier-Stokes (RANS) solver ICARE (using a free-surface tracking method). The coupling between both models is operated in the functional space rather than in the physical space, incident flow parameters being incorporated as forcing terms in modified RANS equations.