Discharge Flow of a Cohesive Granular Media from a Silo.

Cohesion can dramatically affect the flow of granular media. In this Letter, thanks to a cohesion-controlled granular material, we propose to investigate experimentally the effect of the cohesion on the discharge from a silo. We use two geometries, a cylindrical silo and a thin rectangular silo, with an adjustable bottom to control the size of the orifice.

Cohesion-controlled granular material.

We present a simple method to prepare a granular material with a controlled cohesion between particles. The granular material is made of spherical glass beads coated with a polyborosiloxane polymer. This material is proved to be stable in time and nonsensitive to temperature and humidity.

Insights into the rheology of cohesive granular media.

Characterization and prediction of the "flowability" of powders are of paramount importance in many industries. However, our understanding of the flow of powders like cement or flour is sparse compared to the flow of coarse, granular media like sand. The main difficulty arises because of the presence of adhesive forces between the grains, preventing smooth and continuous flows.

Angular particle sliding down a transversally vibrated smooth plane.

We present a theoretical, numerical, and experimental study about the sliding motion of an angular particle down a vibrated smooth plane. The model is based on a Coulomb's friction law with a unique friction coefficient. The model is solved numerically and is tested with controlled experiments.