Ring-like spin segregation of binary mixtures in a high-velocity rotating drum

TL;DR

This study uses molecular dynamics simulations to explore how binary mixtures segregate in a high-velocity rotating drum, revealing ring-like patterns influenced by particle size and density, explained by percolation and buoyancy effects.

Contribution

It introduces a detailed analysis of spin segregation patterns in rotating drums, highlighting the roles of particle size and density, and provides a phase diagram for these segregation states.

Findings

Smaller, heavier particles tend to move towards the drum wall.

Bigger, lighter particles tend to move towards the center.

Segregation patterns are explained by percolation and buoyancy effects.

Abstract

We present molecular dynamics simulations on the segregation of binary mixtures in a high-velocity rotating drum. Depending on the ratio of particle's radius and density, the ring-like spin segregation patterns in radial direction show similarities to the Brazil-nut effect and its reverse form. The smaller and heavier particles are easier to accumulate towards the drum wall and the bigger and lighter ones towards the drum center. Furthermore, we quantify the effects of particle's radius and density on the segregation states and plot the phase diagram of segregation in the ${\rho_b}/{\rho_s}$ - ${r_b}/{r_s}$ space. The observed phenomena can also be well explained by the combined actions, i.e., the percolation effect and the buoyancy effect.