Jesica G. Benito

Arching during the segregation of two-dimensional tapped granular systems: Mixtures versus intruders

We present numerical simulations of binary mixtures of granular disks subjected to tapping. We consider the size segregation process in terms of the arches formed by small and big particles. Although arching has been proposed as one of the chief mechanisms that determines size segregation in non-convecting systems, there is no direct data on arching to support the existing proposals. The pseudo-dynamic approach chosen for this work allows for a straightforward identification of arches in the bulk of the column. We find that, indeed, arch formation and breakage are crucial to the segregation process. Our results show that the presence of large particles induce the formation of more arches than found in mono-sized samples. However, tapping leads to the progressive breakage of big arches where large particles are involved as the segregation process takes place. Interestingly, isolated intruders may or may not rise under tapping depending not only on the size ratio (as it is well known) but also on the degree of ordering of the environment.Graphical abstract

Segregation in a Galton Board

This work deals with a numerical study of the problem of separation of particles with different elastic properties. The separation procedure uses a Galton Board which consist in a bidimensional system of obstacles arranged in a tiangular lattice. Disks of equal diameters but different elastic properties are launched from the top of the device. The Galton Board is commonly used for mixing particles, but here, we intend to find special conditions under which one can use it as a segregating device. We introduce a mixture of particles and generate, through simulations, different conditions to favor the segregation process based on the different elastic coefficients of the particles. We inspect which is the best configuration of size, density of obstacles and wall separation to favor the separations of particles. Our results prove that the Galton Board can be used as a segregation device under certain conditions.

Segregation Effects in Rectangular Piles Built Up by a Moving Injection Device

An experimental study of granular segregation is reported on rectangular grain piles built by dropping simultaneously grains of two different species from a funnel moving back and forth sinusoidally parallel to the length of the pile. Our experimental set‐up allows us to control the following variables during the build‐up of the pile: height of the injection point above the top, amplitude and velocity of its displacement and injection flow rate for each kind of grains. Glass beads of different diameters are used in the experiment. Preliminary experimental results demonstrate that the distance of the injection point from the top of the pile and the amplitude of the motion have the largest influence on the segregation.