Scaling of wet granular flows in a rotating drum

Abstract

In this work, we investigate the effect of capillary forces and particle size on wet granular flows and we propose a scaling methodology that ensures the conservation of the bed flow. We validate the scaling law experimentally by using different size glass beads with tunable capillary forces. The latter is obtained using mixtures of ethanol-water as interstitial liquid and by increasing the hydrophobicity of glass beads with an ad-hoc silanization procedure. The scaling methodology in the flow regimes considered (slipping, slumping and rolling) yields similar bed flow for different particle sizes including the angle of repose that normally increases when decreasing the particle size.

Wet granular flow control through liquid induced cohesion

“…The aim of this work is to explore the effect of liquid induced cohesion on the flow properties of wet granular assemblies at different particle sizes, and to establish a methodology allowing to control and eventually scale the flow of wet particles in a rotating drum. We complete our previous work [16] and we focus mainly on the macroscopic phenomena associated with the collective behaviour of particles. In their investigation of the flow of wet granular assemblies in a rotating drum, several authors including Nowak et al [17], Xu et al [18], Soria-Hoy et al [19] and Tagzes et al [10] varied the liquid content.…”

“…Contact angles of water-ethanol mixtures as a function of the ethanol fraction on silanized and nonsilanized glass. Adapted from Ref [16]…”

Cohesion-driven mixing and segregation of dry granular media

“…2. By analogy to the flow of wet particles in the presence of capillary forces 18,19 , we can infer that the increase of the dynamic angle of repose is because the cohesive forces prevent the rolling and cascading of individual particles in favor of bulk sliding. These experiments show that the cohesive force between particles can be adjusted using the silanization reaction duration, and can also be characterized at the bulk level using the angle of the flow in a rotating drum.

Figure 3( a ) Smoothed dynamic angle of repose as a function of time for dry and cohesive particles of radius 0.85 mm, ( b ) Averaged dynamic angle of repose as a function of the cohesive force after 20 seconds of drum rotation.

…”

“…As a consequence, several studies regard particles as non cohesive 15–17 , but cohesion is always present in most industrial particulate processes, and thus has to be taken into account. In some other studies, cohesion was introduced using various viscous liquids with different capillary forces 14,18–21 . Jarray et al .…”

Liquid migration in flowing granular materials

“…Discrete Elements Method (DEM) simulations were performed using MercuryDPM code [9], with the same drum, particles, and liquid properties as in the experiments performed by Jarray et al [1,10]. The drum was filled to 35% of its volume with monodisperse glass particles, of density ρ = 2500 kg/m 3 and radius r = 1.25 mm.…”