(133a) Effects of Rolling Friction, Cohesion and Size Distribution on the Shear Flow of a Binary Particle Mix

Authors: 
Yang, J., University of California Davis
Bunchatheeravate, P., Vertex Pharmaceuticals
Bullard, J. W., Vertex Pharmaceuticals
Curtis, J. S., University of California Davis
In this study, shear flows of a binary mixture of large and small spherical glass bead particles are modeled using discrete element method (DEM) in order to explore the underlying mechanism of the trend that the shear stress of a binary mixture is larger than that of mono-dispersed particles. The effects of rolling friction, particle cohesion and particle size distribution on the stress behavior are investigated. It is found that the stress for non-rotational particles is larger than that of rotational particles. By implementing the rolling friction into the model, the shear stress decreases with increasing rolling friction. Cohesion between small particles with a mean size of 40 µm is considered. The shear stress decreases with increasing cohesion, since the particles with cohesion become less compacted. The poly-dispersed particle size is represented by setting a number of bins of particles in the DEM simulation. The shear stress from poly-dispersed system matches better with the experimental result than that of mono-dispersed system. It is also found that the particle size (or particle size ratios in binary mixtures) has a significant effect on the contact structure of the whole system and consequently affects the shear stress.