Résumé
This work is devoted to the numerical simulation of dense granular media which interact by frictional contact. We use the Non Smooth Contact Dynamics approach which deals rigourously with contact problems and uses a classical Gauss-Seidel like algorithm. To keep reasonable time of computation, we proceed to different kinds of optimisation. In a first part we develop sequential and parallel implementations (informatic optimisation) and in a second one we introduce a new algorithm based on a conjugate gradient method (algorithmic optimisation). These strategies are efficient and allow to simulate faster granular systems with different and sometimes simultaneous behaviours from solid to liquid. Simulations of flows in rotating drums complete the recent experimental investigations. A numerical sandbox modelling is proposed for replacing analogic sandbox experiments used in the study of tectonic movements.