Horizontal Size Segregation in Granular Matter

When a monolayer of spheres, which is subjected to a circular boundary, is applied with a circular polarized force, an intruder sphere will tend to move to the boundary or the center, depending on its size and mass. We use a molecular dynamics simulation to study this phenomenon. We consider that only pure rolling of spheres occurs and is caused by friction with the supporting plate. The spheres collide elastically with the boundaries and the collision between two spheres is modeled by a linear spring. The phase diagram of segregation, with the diameter ratio and the mass ratio as parameters, is obtained. The border line that separates the two states in the phase diagram shows a positive power relation. PACS numbers: 45.70.Mg, 05.20.-