Abstract
This study aims to assess and analyse the patterns of segregation and stratification in pouring heaps of granular mixtures composed by binary sized and uniformly shaped particles. We present 2D and 3D simulations which respectively build deposits of poured disks and spheres by means of a discrete-element approach known as contact dynamics (CD). In order to identify preferable conditions for segregation and stratification, we try several deposition scenarios varying the pouring flow rate, injection height, heap’s width and mass ratio between large and small grains in our binary samples. Although some authors assert that shape dispersity might not be necessary to obtain stratification, the phenomenon seems hard to seize with mono-shaped granular media as it appears to require a close control on pouring conditions. The introduction of our DEM models and statistical analysis intend to provide examples of what could constitute efficient numerical tools to study the remaining open problems related to heap segregation patterns prediction.
Highlights
Granular flows are often found in natural environments and industry as main mechanism for transport and deposit of geomaterials
Makse et al experimentally triggered stratification by dropping a bi-dispersed mixture composed of small glass beads and larger angular sand grains in a narrow container [12,13,14]
By pouring particles onto a pile, they displayed a pattern with alternating layers of glass beads and sand parallel to the free surface of the heap
Summary
Granular flows are often found in natural environments and industry as main mechanism for transport and deposit of geomaterials. Benito et al provided evidence that stratification could be drawn from pouring binary sized mixtures only made of spherical particles, supporting the previous assertions [2, 3] Their findings were obtained following a study on the influence of experimental parameters including size ratio, mass flux and dropping height. They found out that stratification, for such a mono-shape grain case, needs larger size ratios between the two families of particles, lower feeding rates, and a smaller cell width. Such results have been lately replicated by Zhang et al in 3D discrete-element simulations exposing particle stratification for analogous pouring conditions [21]
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