Laboratory of nonlinear, non-equilibrium and complex systems


Granular gases as a "new state" of matter

A granular material is a conglomeration of discrete solid, macroscopic particles, which can move independently. Some examples of granular materials are coal, sand, rice, coffee, powders. Granular materials do not constitute a single phase of matter but have characteristics reminiscent of solids, liquids, or gases depending on the average energy per grain. If the average distance between granular particles exceeds their dimensions, such system is called granular gas.
Dusty clouds, interstellar dust and planetary rings can be considered as examples of granular gases. Granular particles loose energy during the inelastic collisions, which leads to a rich phenomenology, exhibiting striking differences with equilibrium gases: nonequipartition of energy, non-Gaussianity of the velocity distributions, anomalous diffusion. We study these features in terms of a kinetic theory and computer simulations.