Eur. Phys. J. E 5, 441-444 (2001)
Time of avalanche mixing of granular materials in a half filled drum
S.N. Dorogovtsev1, 2 and J.F.F. Mendes11 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
sdorogov@fc.up.pt
(Received 27 October 2000 and Received in final form 13 March 2001)
Abstract
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
