Compartmentalized granular gases: flux model results

A review is given of our previous work on the clustering phenomenon for vibrofluidized granular matter in an array of connected compartments, being a prime example of spontaneous pattern formation in a many-body system far from thermodynamic equilibrium. Experiments show that when the shaking strength is reduced below a certain critical level, the grains cluster together: first into a subset of the compartments and ultimately, on a much longer timescale, into a single compartment. These experimental observations are explained qualitatively and quantitatively by a dynamical flux model. We discuss several variations on the original system, altering the openings between the compartments, in such a way that the clustering induces convective patterns and directed transport. Here the bifurcational structure becomes more intricate, but is again fully explained by the corresponding flux model.