Segregation of granular media by diffusion and convection - art. no. 011307

A diffusion-convection equation is used to model granular segregation withi n a mixture of particles of different size, shape, or surface structure in a vertical vessel. Convection describes competition between species in vert ical direction whereas random noise (shaking) allows particles to exchange positions. For two species it is shown that the moving grains converge to a unique distribution along the vertical scale. For more than two species it is shown that at least one equilibrium distribution exists (there are exam ples with multiple equilibria). For a class of models with simple competiti on laws, uniqueness of the equilibrium in all dimensions is shown.