Filling a silo with a mixture of grains:
Friction-induced segregation

A. Károlyi ^1,2,3, J. Kertész ¹, S. Havlin ^3,4, H. A. Makse ^3,5 and H. E. Stanley ³

¹ Department of Theoretical Physics, Technical University of Budapest
Budafoki u. 8, 1111 Hungary
² Theoretische Physik, FB 10, Gerhard-Mercator Universität - 47048 Duisburg, Germany
³ Center for Polymer Studies and Physics Department, Boston University
Boston, MA 02215, USA
⁴ Minerva Center and Department of Physics, Bar-Ilan University - Ramat Gan, Israel
⁵ Schlumberger-Doll Research, Old Quarry Road - Ridgefield, CT 06877, USA

(received 17 June 1998; accepted in final form 10 September 1998)

PACS. 83.70Fn - Granular solids.
PACS. 64.75 - Solubility, segregation, and mixing; phase separation.
PACS. 46.10 - Mechanics of discrete systems.

Abstract:

We study the filling process of a two-dimensional silo with inelastic particles by simulation of a granular-media lattice gas (GMLG) model. We calculate the surface shape and flow profiles for a monodisperse system and we introduce a novel generalization of the GMLG model for a binary mixture of particles of different friction properties where, for the first time, we measure the segregation process on the surface. The results are in good agreement with a recent theory, and we explain the observed small deviations by the nonuniform velocity profile.

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