  Granular materials of different sizes are present on the surface of several
atmosphere-less Solar System bodies. The phenomena related to granular
materials have been studied in the framework of the discipline called Granular
Physics; that has been studied experimentally in the laboratory and, in the
last decades, by performing numerical simulations. The Discrete Element Method
simulates the mechanical behavior of a media formed by a set of particles which
interact through their contact points. The difficulty in reproducing vacuum and
low-gravity environments makes numerical simulations the most promising
technique in the study of granular media under these conditions. In this work,
relevant processes in minor bodies of the Solar System are studied using the
Discrete Element Method. Results of simulations of size segregation in
low-gravity environments in the cases of the asteroids Eros and Itokawa are
presented. The segregation of particles with different densities was analysed,
in particular, the case of comet P/Hartley 2. The surface shaking in these
different gravity environments could produce the ejection of particles from the
surface at very low relative velocities. The shaking causing the above
processes is due to: impacts, explosions like the release of energy by the
liberation of internal stresses or the re accommodation of material.
Simulations of the passage of impact-induced seismic waves through a granular
medium were also performed. We present several applications of the Discrete
Element Methods for the study of the physical evolution of agglomerates of
rocks under low-gravity environments.
