Wave EnergyFocusing in aThree-dimensional Numerical WaveTank

Directional wave energy focusing in space is one of the mechanisms that may contribute to the generation of a rogue wave in the ocean. To this effect, in this paper, we study the generation of extreme waves in a three-dimensional numerical wave tank from the motion of a snake wavemaker. The numerical model solves incompressible fully nonlinear free-surface Euler equations for potential flow, using a higher-order Boundary Element Method and a mixed Eulerian-Lagrangian time updating. Recent improvements of this numerical model have consisted in the implementation of the Fast Multipole Algorithm, in order to improve the computational efficiency of the spatial solver. A typical case of a near breaking rogue wave is presented as an application. A description of the particular geometry of such a wave is given, as well as preliminary results for the particle velocities at the surface and under the wave crest.