The role of geometry in the simulation of segregation in rectangular piles

BENITO, J.G.; UÑAC, R.O.; VIDALES, A M; IPPOLITO, I.

Workshop; Southern Workshop on Granular Materials 2012; 2012

In previous presentations, we have shown experimental evidence demonstrating that banding segregation can be present in a quasi-bidimensional pile of glass beads, with the sole condition that particles have an appropiate size ratio and concentration. At this time, we present results of a numerical study on the segregation patterns that show up during the formation of piles of grains with two different sizes. The pile is built up by pouring a certain amount of grains from a certain height. Before pouring, the particles are mixed and have a given concentration of large and small sizes. Different segregation patterns are observed depending on the concentration and on the relative size of the particles. Two different simulation methods are employed: a Discrete Element Method (DEM) and a pseudo-dynamic one (PSDM). This last method only takes into account the excluded volume effect that arise when particles interact, forces are not calculated here. In the former method, we simulate glass spheres and in the second one, we employ disks. A quantification of the different types of segregation patterns arising in the piles is performed through a suitable criteria. Analysis of the contact distribution between particles is also performed to show the differences and coincidences among the different segregation conditions. The role of geometry is put into evidence when comparing the results of PSDM with DEM. We also make a comparison with our own experimental results.