The effect of cohesion on the discharge of a granular material through the orifice of a silo

Abstract

We present the results of both experimental and numerical investigations of the silo discharge for a cohesive granular material. In our study, thanks to a cohesion-controlled granular material (CCGM) we propose to investigate the effect of the cohesive length lc, on the discharge of a silo for two different configurations, one axisymmetrical, and one quasi-2D rectangular silo. In both configurations, an adjustable bottom is used to control the size of the orifice. As observed for cohesionless granular material by previous studies, the mass flow rate and the density through an orifice are mostly controlled by the diameter of the orifice D. The experimental results of the quasi-2D silo are compared with continuum numerical simulations.

Two-dimensional spreading of frictionless adhesive oil droplets

“…39 These studies may provide insight into cohesive systems since the granular capillary length is anaolgous to the cohesion length, introduced recently by Gans and co-workers, which is defined using cohesion-controlled granular material. 22–24 This work expands on our previous work, showing that despite the fact that the oil droplets are granular in nature, with the absence of friction and the presence of an adhesive force, aggregates of these droplets can be described in a manner that would normally be used to describe a continuum liquid. This study enables us to further investigate the boundary between the continuum and the discrete approach for granular systems.…”

“…Recent experiments with a cohesion-controlled granular material reveal a dependence on a fundamental length scale called the cohesive length, which can be determined by balancing cohesion with the force of gravity. 22–24…”

“…[14][15][16][17] For granular materials consisting of dry cohesionless grains, the angle of repose is primarily dependent on the internal friction of a material and it also has a dependence on particle size, shape, and roughness. [17][18][19][20] Investigations into more complex systems where particles are influenced by additional forces such as cohesion, [21][22][23][24][25][26][27] thermal motion, 28,29 and particle flow, [30][31][32] show that the structure of accumulations of granular materials are robust. Recent experiments with a cohesion-controlled granular material reveal a dependence on a fundamental length scale called the cohesive length, which can be determined by balancing cohesion with the force of gravity.…”

“…Recent experiments with a cohesion-controlled granular material reveal a dependence on a fundamental length scale called the cohesive length, which can be determined by balancing cohesion with the force of gravity. [22][23][24] Of particular interest are studies showing that even in systems where friction is negligible, spheres can accumulate with a measurable angle of repose. [33][34][35] Ortiz et al observed that slightly repulsive frictionless colloids would accumulate with a measurable angle of repose while accumulating at a barrier in a microfluidic channel.…”