ABSTRACT
The segregation phenomenon occurs when a granular mixture is perturbed by shaking, rotating or flowing. Many physical processes imply this effect. The friction, percolation, dissipation of energy, collisions are some examples of these processes.The BNE is the first pattern of segregation which was observed. It corresponds to the pattern for which the larger and heavier grains are on the top of the pile. More recently, its reversible effect was observed (Huerta & Ruiz-Suarez 2004). For this last phenomenon, the larger and heavier grains go to the bottom of the pile in opposition to the BNE. A review of both experimental and theoretical works about BNE/RBNE has been recently written (Kudrolli 2004). Some theoretical works have been proposed based on percolation/condensation, geometrical frustration, inertia, thermodynamics effects, etc. However, the physical processes leading to the occurrence of BNE/RBNE segregation are not deeply understood.
