This paper considers the segregation of a granular mixture in a rotatingdrum. Extending a recent kinematic model for grain transport on sandpilesurfaces to the case of rotating drums, an analysis is presented for radialsegregation in the rolling regime, where a thin layer is avalanching down whilethe rest of the material follows rigid body rotation. We argue that segregationis driven not just by differences in the angle of repose of the species, as hasbeen assumed in earlier investigations, but also by differences in the size andsurface properties of the grains. The cases of grains differing only in size(slightly or widely) and only in surface properties are considered, and thepredictions are in qualitative agreement with observations. The model yieldsresults inconsistent with the assumptions for more general cases, and wespeculate on how this may be corrected.
展开▼
