Open boundary conditions and coupling methods for ocean flows

International audienceDesigning efficient open boundary conditions is an old problem in ocean modelling. This problem is of particular importance with the present strong development of regional ocean modelling systems, but it has still no fully satisfying solution. In this talk, we will report some ideas and results on this problem, in particular in connexion with the theory of absorbing boundary conditions. We will also address the problem of designing interface conditions for coupling models with different physics (e.g. ocean/atmosphere, or coastal ocean / large scale ocean). We will show that using improved coupling algorithms (like Schwarz methods) with regard to usual ad hoc methods can lead to significant differences in the model solutions, and that the efficiency of such iterative algorithms is closely linked to the open boundary problem