Segregation and coarsening of granular mixture in a rotating tube

We present results of long-time simulations of a model of the segregation of a granular mixture in a horizontal half-filled rotating tube. We show, that the fast segregation of a homogeneous mixture into the bands of pure species is followed by the long coarsening period, with decreasing number of the bands, that leads to the equilibrium state, in which the number of bands fluctuates about its mean value. Our results are in a good agreement with the recent experiments.