Band-in-band segregation of multidisperse granular mixturesM. Newey1, J. Ozik1, S. M. van der Meer2, E. Ott1 and W. Losert1
1 Institute for Research in Electronics and Applied Physics, University of Maryland College Park, MD 20742-3511, USA
2 Department of Applied Physics and J.M. Burgers Centre for Fluid Dynamics University of Twente - P.O. Box 217, 7500 AE Enschede, The Netherlands
(Received 30 September 2003; accepted in final form 16 February 2004)
Radial and axial segregation is investigated experimentally in polydisperse mixtures of granular materials rotated in a long, partly filled, horizontal cylinder. Radial segregation by size is observed in all polydisperse mixtures. Axial segregation, with smaller-size particles forming bands within bands of larger-size particles, is observed for mixtures of 3 sizes. In addition, bands in ternary mixtures oscillate axially under some conditions. It is observed that the surface flow speeds depend on the particle size, both in the mixed and segregated case. A simple microscopic model based solely on different frictional properties of three particles yields qualitatively similar results.
45.70.Mg - Granular flow: mixing, segregation and stratification.
64.75.+g - Solubility, segregation, and mixing; phase separation.
05.65.+b - Self-organized systems.
© EDP Sciences 2004