Eur. Phys. J. E (2012) 35: 38
https://doi.org/10.1140/epje/i2012-12038-5

Regular Article

Segregation in arch formation

¹ Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, 30161-970, Belo Horizonte, MG, Brazil
² Departamento de Física e Matemática, CEFET-MG, and Instituto Nacional de Ciência e Tecnologia - Sistemas Complexos, INCT-SC, Rio de Janeiro, Brazil

^* e-mail: caiofrancam@gmail.com

Received: 27 February 2012
Revised: 8 May 2012
Accepted: 15 May 2012
Published online: 25 May 2012

Abstract

We report new segregation phenomena in the clogging arches formed during the discharge of granular piles. Results from molecular dynamics simulations show segregation effects with respect to both size and density ratios used in piles built with bidisperse mixtures of grains. The clogging arch is preferentially constituted of large grains when size bidisperse piles were discharged, whereas for density bidisperse mixtures there is a predominance of light grains in the arch for large orifice widths but, for small widths, an inversion in the preference is observed, with a slightly higher incidence of heavy grains forming the arches. We present arguments based on the reverse buoyancy effect and the statistics collected for the avalanche size distributions to explain how these effects can be understood as a crossover between two different segregation mechanisms acting independently at small and large orifice width limits.