Vibrated granular bed on a bumpy surface.

We investigate effects of physical characteristics of the vibrating base in a vibrated granular bed system on the bulk granular behavior of the bed using molecular dynamics simulations. With a vibrating base that exhibits low coefficient of restitution for particle-base collisions, a monolayer of granular materials was observed to form dynamically on the surface of the base. Such a system was shown to be both qualitatively and quantitatively equivalent to one with a bumpy base composed of discrete solid particles undergoing the same type of imposed oscillatory motion. The "bumpiness" of such a base, as defined by the size of particles constituting the vibrating base, was also found to have insignificant effects on the behavior of the bulk granular materials. The observations made in this study may point toward a possible methodology to model vibrating granular bed systems with inelastic bases using continuum theories.