Numerical modelling of tidal currents along the west European continental shelf

A tidal simulation, with a 2D code (TELEMAC) has been performed by the L.N.H. (Laboratoire National d'Hydraulique of Electricite de France) during a complete moon cycle in order to calculate current fields in the English Channel and the close Atlantique. These tidal currents combined with wind-induced-currents are aimed at predicting the movements of polluted matters. They will be used also as boundary conditions for modelling local areas. The study area as it ends farther off the continental shelf encloses an exceptionnal number of elements (20,000). However, the recent improvements in numerical methods and computers allow this calculation with a reasonable cost. The finite element technic is also used very favourably as the surface of an element decreases from 500 square miles along the West boundary to 1 square mile along the coast. Consequently, a new performance has been reached : modelling tidal currents inside a very large oceanic area with an extreme precision along the coast.