Numerical simulations of the dynamics of discrete structures in presence of numerous impacts and frictional contacts lead to CPU-intensive large time computations. To deal with such realistic assemblies, numerical tools have been developed, in particular the method called nonsmooth contact dynamics (NSCD). Such modeling has to deal with discreteness and nonsmoothness, such that domain decomposition approaches for regular continuum media have to be rethought. We present further two domain decomposition methods linked to Schwarz and Schur formalisms. Scalability and numerical performances of the methods for 2D and 3D granular media are studied, showing good parallel behavior on a supercomputer platform. The structural behavior of dense granular packing is herein used to introduce a spacial multilevel preconditioner with a coarse problem to improve convergence in a space-time approach.
