Ring-like spin segregation of binary mixtures in a high-velocity   rotating drum
  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. 
Decai Huang, Ming Lu, Gang Sun, Yaodong Feng, Min Sun, Haiping Wu,   Kaiming Deng
cond-mat.soft