8 pages, 10 figures; OMAE2008, 27th International Conference on Offshore Mechanics and Arctic Engineering. We slightly modified the paper according to referees comments. Other authors papers and animations related to this work can be downloaded from: http://www.cmla.ens-cachan.fr/fileadmin/Membres/dutykh/International audienceThe purpose of this communication is to discuss the simulation of a free surface compressible flow between two fluids, typically air and water. We use a two fluid model with the same velocity, pressure and temperature for both phases. In such a numerical model, the free surface becomes a thin three dimensional zone. The present method has at least three advantages: (i) the free-surface treatment is completely implicit;...