Colored sandpile

After the introduction of the sandpile model a number of different variants have been studied. In most of these models sand particles are indistinguishable. Here, we have painted the sand particles using a few distinct colors, and restrict them to move in linear trajectories only along their assigned lattice axes, one axis reserved for one color. Different colored particles interact among themselves through the toppling of unstable sand columns. Consequently, the avalanches or in general the self-organization processes in the sandpile have no overall preferred direction, though the individual particles execute directed motion. For such non-Abelian colored sandpiles the steady states are found to be different, as well as the avalanche size distributions. This sandpile so defined has a nontrivial spatial structure and belongs to a different universality class of sandpile models. The Dynamics of a granular heap with grains of different colors and properties may be described using this sandpile.