Particle shape-induced axial segregation of binary mixtures of spheres and ellipsoids in a rotating drum

Particles with different properties such as size and shape in rotating drums tend to segregate axially to different sections. In this work, we report an interesting phenomenon that for ellipsoid-sphere mixtures, spheres tend to segregate axially to the middle section of the drum. The axial segregation becomes severe and reaches a maximum at aspect ratios of 0.67 and 2.0. Further increasing the deviation leads to a lower segregation degree. It is observed that the acceleration effect on particles by the frictional end walls induces the axial flow of particles. Both ellipsoids and spheres in the outer region of the transverse slice tend to migrate to the middle section while particles in the inner region migrate to the end walls. Generally, the axial flow induced by the frictional end walls and the radial segregation are essential for the development of particle shape-induced axial segregation.