Pattern scaling in the axial segregation of granular materials in a rotating tube

Christopher R. J. Charles; Zeina S. Khan; Stephen W. Morris

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Pattern scaling in the axial segregation of granular materials in a rotating tube

Christopher R. J. Charles·Zeina S. Khan·Stephen W. Morris

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Abstract

Granular mixtures frequently segregate by grain size along the axis of partially-filled, horizontal, rotating tubes. When segregation approaches saturation at the surface, a well-defined pattern of bands with wavelength $λ$ emerges. The long-term dynamics of the pattern involves a much slower coarsening process. We characterized the initial saturated wavelength $λ$ as a function of the diameter of the tube $D$ for a filling fraction of 30 %, for $1.9 {\rm cm} \leq D \leq 11.5 {\rm cm}$. We also studied the initial growth-rate of the bands as $D$ varies. We find that $λ/D$ is not constant, but rather increases rapidly for small $D$. The growth-rate of bands decreases with smaller $D$ and segregation is suppressed completely for sufficiently small $D$. These relatively simple features are not captured by any of the existing models of axial segregation.

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Christopher R. J. Charles, Zeina S. Khan, Stephen W. Morris. 2005-01-25. Pattern scaling in the axial segregation of granular materials in a rotating tube. https://arxiv.org/abs/cond-mat/0501606

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