Flow of anisometric particles in a quasi-two-dimensional hopper

Abstract

The stationary flow field in a quasi-two-dimensional hopper is investigated experimentally. The behavior of materials consisting of beads and elongated particles with different aspect ratio is compared. We show, that while the vertical velocity in the flowing region can be fitted with a Gaussian function for beads, in the case of elongated grains the flowing channel is narrower and is bordered with sharper velocity gradient. For this case, we quantify deviations from the Gaussian velocity profile. Relative velocity fluctuations are considerably larger and slower for elongated grains.

Fluctuation of particles during funnel flow discharge from flat‐bottomed silos

“…The velocity distribution curve gradually flattens along the upward direction and eventually forms a plateau in the horizontal central zone, that is, a plug flow zone is formed in the upper part of the flowing zone. Such phenomenon has also been experimentally observed for funnel flow discharge 21–25 . Szabo et al 25 found the formation of plug flow zone was closely related to the particle shape.…”

“…Such phenomenon has also been experimentally observed for funnel flow discharge 21–25 . Szabo et al 25 found the formation of plug flow zone was closely related to the particle shape. Their experimental results showed that the position of plug flow zone was closer to the outlet for longer grains.…”

“…For funnel flow discharge, the flowing zone width first increases with vertical position and then keeps nearly constant 18–20 . Experimentally, it has been found that granular materials in the upper part of the flowing zone could be in plug flow state and notable velocity gradient only appears in the narrow shear region in between the flowing and stagnant zones 16,21–25 . Thus, if we consider the interface between flowing and stagnant zones as a rough surface, the flowing pattern of funnel flow is actually the same as that of mass/semi‐mass flow.…”

Intermittent flow and transient congestions of soft spheres passing narrow orifices

“…Most experiments and numerical simulations have been performed with hard monodisperse spherical grains in the past. Few experiments of non-spherical shapes 19,[26][27][28] demonstrated that many features of the discharge can be compared to those of spheres when an effective particle radius is introduced. Examples of numerical simulations of silo discharge of nonspherical particles with multisphere-DEM include rods 29 and mixtures of spherical and rodlike grains.…”

Mechanically driven active and passive grains as models for egress dynamics

“…In all discharge experiments, we placed the capsules initially in random orientations. However, elongated grains typically display alignment near the outlet of a discharging hopper [21,22], an aspect that may be influenced by activity of the grains. In Fig.…”