Granular Segregation in Tapered Rotating Drums

TL;DR

This study uses simulations to analyze how tapering angles in rotating drums influence granular segregation, revealing that axial segregation results from radial segregation and drum shape, and can be modeled similarly to chute flows.

Contribution

It demonstrates that tapered rotating drums can serve as simple experimental setups to study granular segregation and validate shallow flow theories.

Findings

Axial segregation depends on the drum's tapering angle.

Radial and axial segregation are interconnected phenomena.

Tapered drums can be used to test theories of shallow gravity-driven flows.

Abstract

We study the granular segregation in a tapered rotating drum by means of simulations. In this geometry, both radial and axial segregation appear, the strength of which depends on the filling fraction. We study the effect of the drum's tapering angle on the segregation speed and show that, coherently with several recent studies, the axial segregation is due to the combined effect of the radial segregation and the shape of the drum. We show that the axial segregation behaves in a way analogous to the one found in chute flows, and corresponds to previous theories for shallow gravity driven surface flows with diffusion. By means of this analogy, we show that tapered drums could be the simplest experimental set-up to obtain the free parameters of the theory.