Experimental investigation into the wet non-spherical granular segregation and mixing in rotating drums

This paper experimentally investigates the wet non-spherical granular segregation in a quasi-2D rotating drum. The granular mixtures consisted of spherical POM beads and non-spherical red beans. To explore the interlocking effect resulting from particle shape, a long axis ratio was defined. Experimental results reveal that both the long axis ratio and the liquid content play crucial roles in wet non-spherical granular segregation. The steady-state segregation index decreases monotonically with the increase of long axis ratio. As the long axis ratio increases, the average velocity and granular temperature of spherical POM beads increase. Both properties also increase monotonically with liquid content. The dynamic angle of repose increases with the increasing liquid content, whereas the steady-state segregation index decreases. Reverse segregation does occur in a dry non-spherical mixture with a size ratio of 1.42, indicating that the shape effect appears to enhance the degree of reverse segregation appreciably.