Collapse of a cohesive granular column

Abstract

The collapse of a quasi-two-dimensional column of cohesive granular media is investigated experimentally and numerically in the framework of a continuum model. The configuration is an initial parallelepiped-shaped granular pile, which is suddenly released by opening a retaining door. The experiments rely on a model material developed by Gans et al. (Phys. Rev. E, vol. 101, 2020, 032904) made of silica particles coated with polyborosiloxane, for which the adhesive interparticle force can be tuned by controlling the thickness of the coating. Numerically, the collapse is simulated using a simple cohesive rheological model implemented in a two-dimensional Navier–Stokes solver. We investigate the role of cohesion on the stability of the column, the mode of failure, the flow dynamics and the geometry of the final deposit. Our results show that the continuum model captures the main features observed experimentally.

The combined effect of cohesion and finite size on the collapse of wet granular columns

“…However, for a tall column, its stability depends not only on ξ but also on the aspect ratio a . This conclusion is well consistent with those obtained from our simulations and experiments presented in the phase diagram, which is also similar to the analysis of column stability using the cohesion length c proposed by Gans et al 28 The inverse dependency of the critical value of ξ on a predicted by eqn (7) for tall columns to remain stable can properly describe the simulation and experimental results in the phase diagram for various parameters and conditions.…”

“…More importantly, there may be coupling effects between these factors, which poses a great challenge to identify relevant cohesive parameters that control the dynamics and the deposit of collapsed material. 28,29 Recently, several alternative dimensionless parameters have been proposed, and their applicability in describing the stability, dynamics, and flow properties of cohesive granular materials under different conditions has also been demonstrated, 30,31 which is extremely helpful when developing theoretical models to describe rheological behaviors of these materials.…”

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.…”

“…14–17 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. 17–20 Investigations into more complex systems where particles are influenced by additional forces such as cohesion, 21–27 thermal motion, 28,29 and particle flow, 30–32 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. 22–24…”