Segregation of granular mixtures in a spherical tumbler

Abstract

Segregation of polydisperse granular materials in rotating containers is a ubiquitous but still not satisfactorily understood phenomenon. This study describes axial segregation of bidisperse granular mixtures of glass beads in a spherical container, rotating about its horizontal axis. Depending on the filling fraction of the mixer and on the composition of the mixture, qualitatively different spontaneously formed patterns are observed. For technical applications, the well-localized segregated bands allow a convenient separation of individual components of the mixtures. It is particularly surprising that the initial compositions of the granular mixtures have a fundamental influence on the location of the segregated bands. This evidences a collective pattern forming mechanism. The spontaneous formation of these bands cannot simply be traced back to individual particle dynamics. Existing models for segregation in spherical mixers are critically examined and extensions are suggested.

Review of noninvasive methods to characterize granular mixing

“…Collected data was then used to compare the speed and accuracy of different image analysis algorithms and regression models in determining mixing times. Development of material bands in a spherical tumbler was investigated by Finger et al [14]. The spherical vessel was made of transparent material and images were taken from the top.…”

General fabrication of hollow colloids from polymer self-assembly cavity-forming strategy

“…21 Additionally, as a characteristic hollow architecture, hollow tumblers, which are composed of a hollow shell and an asymmetrical center of gravity, are well known as artificial balance devices, with their earliest history dating back to the Tang Dynasty as the fashionable gyroscope incense burner in the palace. 22,23 The self-stabilization principle of hollow colloids associated with the tumbler structure has been reported, [24][25][26] and is distinct from that of yolk-shell structures. 27 However, it has not been successfully emulated in the micro/nanoscience of synthesis.…”

DEM modelling and analysis of the mixing characteristics of sphere-cylinder granular mixture in a rotating drum

“…Although these methods are effective in characterization, they are destructive to the structure [3]. Tomography, velocity measurement and spectroscopy can characterize and evaluate the flow and mixing behavior of particles in a rotating drum without destroying the granular system [4][5][6][7][8][9][10], while these methods are really difficult to visualize and quantify the motion behavior of internal particles in the mixing process. In addition, the mixing behaviors are also closely related to the micromechanical properties (e.g., inter-particle interaction forces) of the system, which are hard to be monitored or characterized in-situ in physical experiments.…”