Segregation-driven organization in chaotic granular flows
- R. R. McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL 60208
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Edited by Andreas Acrivos, City College of the City University of New York, New York, NY, and approved July 30, 1999 (received for review April 21, 1999)
Abstract
An important industrial problem that provides fascinating puzzles in pattern formation is the tendency for granular mixtures to de-mix or segregate. Small differences in either size or density lead to flow-induced segregation. Similar to fluids, noncohesive granular materials can display chaotic advection; when this happens chaos and segregation compete with each other, giving rise to a wealth of experimental outcomes. Segregated structures, obtained experimentally, display organization in the presence of disorder and are captured by a continuum flow model incorporating collisional diffusion and density-driven segregation. Under certain conditions, structures never settle into a steady shape. This may be the simplest experimental example of a system displaying competition between chaos and order.
Footnotes
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↵ * Present address: Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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↵ † Present address: Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15261.
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↵ ‡ To whom reprint requests should be addressed. E-mail: ottino{at}chem-eng.nwu.edu.
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This paper was submitted directly (Track II) to the PNAS office.
- Abbreviation:
- KAM,
- Kolmogorov-Arnold-Moser
- Copyright © 1999, The National Academy of Sciences
