International audienceGranular matter flows naturally occur on small or large bodies due to gravity. Their simulation allows a better understanding of the dynamics of these bodies. However many numerical simulations operate with periodic boundary conditions for convenience , or with static grain boundaries that do not reproduce the rolling and friction effects expected at the interface. This work not only shows that boundary conditions have a long-range effect within the flow , but that dissipative effects induced by flat walls cannot be neglected compared to using static grain boundaries
