Granular mixtures discharging through a silo with eccentric orifice location

TL;DR

This study uses DEM simulations to analyze granular flow in a silo with eccentric orifices, revealing how mixture composition and orifice placement affect flow dynamics, velocity profiles, and flow rates.

Contribution

It introduces a modified Beverloo scaling for lateral orifice flow and examines the impact of mixture composition and orifice spacing on flow behavior.

Findings

Flow rate decreases with more dumbbells due to increased friction.

Self-similar velocity profiles are observed across different orifice widths.

Interaction zones between orifices influence flow rate and shear stress.

Abstract

We used the discrete element method (DEM) to study the flow dynamics of a mixture of dumbbells and discs for two silo cases: 1. orifice situated on the lateral wall and 2. multiple orifices placed on the base of a two-dimensional silo. The time-averaged flow fields of various parameters like velocity, area fraction, pressure, shear stress etc, obtained from coarse-graining technique are presented for both the above-mentioned cases. A modified Beverloo scaling is reported for the flow discharging through the lateral orifice. The dynamic friction is found to increase with an increase in the addition of dumbbells. This resulted in a decrease in the flow rate through a lateral orifice with the addition of dumbbells. Self-similar velocity profiles are observed for mixtures for the whole range of lateral orifice widths studied. The flow rate decreases with an increase in the inter-orifice distance L/d for the multiple orifice case. The velocity profile and flow fields revealed an interaction zone between the two orifices at small L/d which is almost absent when the orifices are wide apart. This interaction zone or flow through an orifice influenced by the presence of an adjacent orifice is the reason for a higher velocity above each of the orifices thus resulting in a higher flow rate at small L/d. The stagnant zone between the orifices is found to expand with an increase in the inter-orifice distance which yields in an increase in the shear stress between each of the orifices and the stagnant zone.