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

Huang Decai, Lu Ming, Sun Gang, Feng Yaodong, Sun Min, Wu Haiping, and Deng Kaiming

Phys. Rev. E 85, 031305 – Published 21 March 2012

Abstract

This study presents molecular dynamics simulations on the segregation of binary mixtures in a high-velocity rotating drum. Depending on the ratio between the particle radius and density, similarities to the Brazil-nut effect and its reverse form are shown in the ringlike spin segregation patterns in radial direction. The smaller and heavier particles accumulated toward the drum wall, whereas the bigger and lighter particles accumulated toward the drum center. The effects of particle radius and density on the segregation states were quantified and the phase diagram of segregation in the $ρ_{b} / ρ_{s}$ - $r_{b} / r_{s}$ space was plotted. The observed phenomena can be explained by the combined percolation and the buoyancy effects.

Received 15 November 2011

DOI:https://doi.org/10.1103/PhysRevE.85.031305

Authors & Affiliations

Huang Decai^1,*, Lu Ming², Sun Gang^3,†, Feng Yaodong^1,3, Sun Min¹, Wu Haiping¹, and Deng Kaiming¹

¹Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
²School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
³Beijing National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

^*hdc@mail.njust.edu.cn
^†gsun@aphy.iphy.ac.cn

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Vol. 85, Iss. 3 — March 2012

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Images

Figure 1
A snapshot of system at the beginning of simulation.Reuse & Permissions
Figure 2
(a) Image of the S-type system after 500 rotations. The densities of both bigger particles (open symbols) and smaller particles (solid symbols) are of the same value, $ρ_{b} = ρ_{s} = 1.0 \times 10^{3} kg / m^{3}$ . The radii of particles are for different sizes, $r_{b} = 1.5 mm$ and $r_{s} = 1.0 mm$ , respectively. (b) Evolutions of the center positions (solid symbols) and the angular velocity (open symbols) of bigger and smaller particles corresponding to the system of (a). The square and circle symbols are results for the bigger and smaller particles, respectively.Reuse & Permissions
Figure 3
(a) Image of the D-type system after 500 rotations. The radii of both heavier particles (solid symbols) and lighter particles (open symbols) are of the same size, $r_{h} = r_{l} = 1.5 mm$ . The densities of particles are for different values, $ρ_{h} = 3.0 \times 10^{3} kg / m^{3}$ and $ρ_{l} = 1.0 \times 10^{3} kg / m^{3}$ , respectively. (b) Evolutions of the center positions (solid symbols) and the angular velocity (open symbols) of bigger and smaller particles corresponding to the system of (a). The circle and square symbols are results for the heavier and lighter particles, respectively.Reuse & Permissions
Figure 4
Combined size and density segregation patterns of binary mixtures after 500 rotations. The radii of bigger particles (open symbols) and smaller ones (solid symbols) are for different sizes, $r_{b} = 1.5 mm$ and $r_{s} = 1.0 mm$ , respectively. (a) An S+D-type system. The densities of bigger and smaller particles are set to $ρ_{b} = 1.0 \times 10^{3} kg / m^{3}$ and $ρ_{s} = 3.0 \times 10^{3} kg / m^{3}$ , respectively. (b) An S-D-type system. The densities of bigger and smaller particles are set to $ρ_{b} = 3.0 \times 10^{3} kg / m^{3}$ and $ρ_{s} = 1.0 \times 10^{3} kg / m^{3}$ , respectively.Reuse & Permissions
Figure 5
Dependence of the segregation index $χ$ on the radius ratio $ρ_{b} / ρ_{s}$ . The radius ratio values $r_{b} / r_{s}$ are 1.5 (square symbols) and 2.0 (circle symbols), respectively. The open symbols are for radii of $r_{b} = 1.5 mm$ and $r_{s} = 1.0 mm$ , $r_{b} = 2.0 mm$ and $r_{s} = 1.0 mm$ ; the solid symbols $r_{b} = 2.25 mm$ and $r_{s} = 1.5 mm$ , $r_{b} = 3.0 mm$ and $r_{s} = 1.5 mm$ . As $ρ_{b} / ρ_{s}$ increases, the system moves from BNE to RBNE. The dashed line corresponds to the boundary of BNE and RBNE. The solid lines are guides for the eye.Reuse & Permissions
Figure 6
Phase diagram of the binary mixtures in the $ρ_{b} / ρ_{s}$ - $r_{b} / r_{s}$ space. The upward-pointing triangles and downward-pointing triangles represent the segregation patterns of the Brazil-nut effect and Reverse Brazil-nut effect. The solid lines show the boundaries of two segregation patterns.Reuse & Permissions

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