Granular materials are ubiquitous in many industrial processes
such as in construction, food industry and pharmaceutical industry.
Understanding the response of granular materials to excitation,
could help to improve several granulate handling operations in
those industries. It is often said that granular materials behave
sometimes as a solid, other times as a liquid or even a gas (Jaeger
et al., 1996). Besides resembling those states of matter, there are
situations where grains behave in their own particular way, thus
leading many to talk about the “granular state”. Common examples
of granular exclusive behavior is the flow at constant rate in hourglasses
(Wu et al., 1993), or the ability to store grains in high rise
structures (silos).