DEM study of spatiotemporal segregation in cylindrical containers

Objective The arrangement of dry, mono- and bidisperse granular systems composed of spherical particles, dynamically introduced from a central inlet under the effect of gravity, is being investigated within a cylinder with frictionless walls. Methods The analysis, performed using 3D Discrete Element Modeling (DEM), examined the arrangement and structure of granular systems with an 1:3 particle diameter ratio and varying mass fractions. The analysis focuses on the temporal and spatial evolution of kinetic segregation, the ordering of the systems, and the development of different types of interactions (particle-particle and particle-wall). Additionally, the 2D arc of the upper surface of the particle system is described using several complementary methods for a quick determination of the interstitial air volume and the void fraction within the granular systems. For the analysis of the effect of dynamic filling, static, space-filling samples were created. A detailed research plan was prepared to thoroughly document the computational methods of the study. Results Based on the incoming mass fraction into the same system, 6 segregation 3D zones can be distinguished. Fractures (cracks) form in the framework of the mono-disperse particle system early in its arrangement within the container. The resulting concave surface can be well approximated with linear and quadratic curves. The average normal force acting on the volume units of the smaller particles is 1.7–2.8 times greater than that of the larger ones. Conclusions The temporal segregation of particles barely depends on size. The entry of small particles at a 10% mass fraction into the system results in large-scale segregation and the rearrangement of the particle framework. The relationship between the number of contacts of the granular system's particles and the cylinder's bounding elements is exponential in quasi-static states.