SUBHARMONIC SURFACE-WAVES IN VIBRATED GRANULAR MEDIA

Using a simplified model of a dissipative discrete-particle fluid we s tudy the formation of surface waves under vertical vibration. The only dissipative forces included in this two-dimensional molecular dynamic s simulation act normally to the line of contact during collisions; tr ansverse frictional forces commonly used in granular models are not re quired. Depending on the parameters, surface waves are observed to for m with a half or a quarter of the driving frequency. (C) 1998 Elsevier Science B.V. All rights reserved.