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Active Granular Matter
We discuss experiments designed with granular matter to develop the
physics of self-propelled particle systems which move and interact via
simple physical rules. The shape and mass distribution of a particle
can be exploited to fabricate elements which perform random motions or
directed random walks on a vibrated plate. The number density is
varied from the dilute to the dense regime where they can move freely
or suffer dynamical arrest. We will discuss the self-diffusion and
density fluctuations of the self-propelled particles as a function of
their degree of shape anisotropy and self-propulsion. We will give
several examples of dynamic collective behavior which arises including
clustering, swarming, and vortex motion depending on the individual
interactions with neighboring particles. We will further examine the
broader role of particle shape and discuss the application of models
drawn from polymer physics on the packing and dynamics of granular
matter.
