Résumé
This paper describes CFD of incompressible air-water flows by solving Euler equations with a two phases flow model leading to an hyperbolic system of conservation laws solved with a finite volume discretization on unstructured grids. An artificial compressibility approach allows a fully explicit scheme for an efficient parallel implementation. The numerical model is based on a low Mach number preconditioning and a second order Riemann solver. Applications to breaking waves on a 15% slope with and without influence of macroroughness are performed concerning impact and run-up processes on the beach. INTRODUCTION Great improvements have been brought to the knowledge of the hydrodynamics and the general processes occurring in the surf zone, widely affected by the breaking waves (Peregrine 1983, Christensen et al. 2002). Indeed, the breaking waves play a very important role in marine hydrodynamics, both for ocean physics and engineering applications. Breaking is the most dominant phenomenon in surface wave energy budget. In the naval hydrodynamics context, as for coastal dynamics, a reliable and fast model is necessary to perform parametric investigation to optimize sea defence systems. In particular, kinematics of impact and run up on structures and beaches are drastically important in the case of hazardous events like surges and tsunamis. Concerning wave breaking modelling, the classical full Navier-Stokes solvers are time consuming (e.g. Vincent et al 2004, Guignard et al 2001, Biausser et al 2004) whereas fast models based on Boussinesq equations are unable to compute wave breaking (Grilli et al, 1989, 2001). Herein a new fast three-dimensional two phases flow solver is presented, based on a finite volume discretization on unstructured grids with subdomains decomposition allowing an efficient parallel implementation. This model has already been validated on Yasuda et al (1997) experimental and numerical test case with convincing numerical performances and computational time (Helluy et al, 2005).