Reversing the Brazil Nut Effect
GRASP, Institut de Physique B5a, Université de Liège, 4000, Liège, Belgium
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Published online: 6 December 2005
We propose a lattice model for studying the Brazil Nut Effect (BNE), i.e. the phase segregation occuring when a granular material is vertically shaked. The model considers the tap intensity and the mobility μ of the grains as the main physical parameters. Different mobilities for different grain species lead to segregation (BNE) patterns, reverse segregation (RBNE) patterns, “sandwhich" layered structures or vertical domains. A phase diagram (decompaction χ, mobility difference between both species Δμ) is obtained in which the different phases are emphasized. In a narrow region of the diagram, different phases coexist. It is shown that the BNE segregation could be reversed by increasing the tap intensity or the characteristics of the grains. Numerical results are compared with earlier experimental works.
© EDP Sciences/Società Italiana di Fisica/Springer-Verlag, 2005