Size-induced axial segregation of ellipsoids in a rotating drum

Granular materials of different sizes and shapes in a rotating drum tend to segregate in the axial direction. In the past, extensive numerical studies have been conducted for spherical particles, showing the phenomenon of band formation. However, the axial size-induced segregation of non-spherical particles receives limited attention. In this work, we report an interesting finding of band formation for ellipsoidal particles with aspect ratio varying from 0.5 to 2.0. The results show that for ellipsoids, two weak bands appear in the vicinity of endwalls, indicating that low flowability of ellipsoids reduces the tendency of band formation. Moreover, for different shaped par-ticles, small particles in the bands come from different regions. The results also illustrate that the radial size-induced segregation pattern develops quickly, with small particles located at the centre and then the small particles tend to migrate along the drum to form bands.