Eur. Phys. J. E 5, 441-444 (2001)
Time of avalanche mixing of granular materials in a half filled drumS.N. Dorogovtsev1, 2 and J.F.F. Mendes1
1 Departamento de Física and Centro de Física do Porto, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal
2 A.F. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia
(Received 27 October 2000 and Received in final form 13 March 2001)
The avalanche mixing of granular solids in a slowly rotated 2D upright drum is studied. We demonstrate that the account of the difference between the angle of marginal stability and the angle of repose of the granular material leads to a restricted value of the mixing time for a half filled drum. The process of mixing is described by a linear discrete difference equation. We show that the mixing looks like linear diffusion of fractions with the diffusion coefficient vanishing when is an integer part of . Introduction of fluctuations of suppresses the singularities of and smoothes the dependence .
64.75.+g - Solubility, segregation, and mixing; phase separation.
45.70.Mg - Granular flow: mixing, segregation and stratification.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001