Vendredi 13 novembre 2026 à 11h00 ; salle 259, IUSTI
Abstract: Granular materials and suspensions are always considered as athermal systems. However, one may wonder what happens when a granular material is submitted to thermal motion. To answer this question, we experimentally study a dense colloidal suspension in a microfluidic drum geometry. This suspension is made of silica particles that are heavy enough to sediment and form a well-defined pile, but small enough to remain sensitive to Brownian motion, and the relative effect of the weight and the thermal agitation is simply controlled by the particle size.
In this presentation, I will answer three main questions about a pile of Brownian grains:
- 1) Does it reach equilibrium after sedimentation or does it continue to evolve with time?
- 2) Does it always flow when inclined or can it develop an angle of repose?
- 3) What happens if you mix big particles (almost athermal) and small particles (more sensitive to thermal motion)?