Mixing of Granular Materials in Slowly Rotated Containers

J. J. McCarthy, Troy Shinbrot, Guy Metcalfe, J. Eduardo Wolf, Julio M. Ottino*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


Noncohesive granular materials in slowly rotated containers mix by discrete avalanches; such a process can be described mathematically as a mapping of avalanching wedges. A natural decomposition is thus proposed: a geometrical part consisting of a mapping wedge → wedge, which captures large-scale aspects of the problem; a dynamical part confined to the avalanche itself, which captures details emanating from differences in size/density/morphology. Both viewpoints are developed and comparisons with experiments are used to verify the predictions of the models. In this article, we develop a model of granular mixing and show how to extend the model in order that it may: (1) handle complicated geometries, (2) be applicable for 3-D mixers, (3) rapidly test mixing enhancement strategies, and (4) incorporate differences in particle properties. In addition, an optimal fill level is determined for several 2-D mixing geometries, and a novel hybrid - geometrical/dynamical - computational technique is proposed. By merging the geometrical and dynamical viewpoints, this technique reduces the computational time of a typical molecular-dynamics-type simulation by a factor of 15. The ultimate goal is to provide fundamental understanding and tools for the rational design and optimization of granular mixing devices.

Original languageEnglish (US)
Pages (from-to)3351-3363
Number of pages13
JournalAIChE Journal
Issue number12
StatePublished - Dec 1996

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • Chemical Engineering(all)


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