Molecular dynamics studies of grain segregation in sheared flow

Size segregation is a widely observed consequence of sheared flow in granular media, in which the larger grains rise to the upper surface of the bulk, despite the fact that all grains have the same material density. A two-dimensional molecular dynamics study of the phenomenon is described in this paper. The grains are represented by inelastic disks and the flow occurs down an inclined slope with a rough base. The simulations readily reproduce the segregation effect; the results of a series of measurements of various aspects of this so-called “inverse grading” are reported.