Pierre Jop (Surface du Verre et Interfaces, CNRS/Saint-Gobain, Aubervilliers)

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2 octobre 11:30 » 12:30 — Bibliothèque PCT - F3.04

Encounter between a granular flow and a liquid : erosion and accretion

Blending grains with a liquid is often the first step in an industrial process, but the triphasic nature of the medium yields general descriptions difficult : Cohesion induced by capillary bridges and the progression of liquid in the system create boundaries between zones of different mechanical behavior. Such spatial heterogeneities need to be erase during mixing steps for example. While the static behavior of a homogeneous, partially saturated media is rather well understood, the time evolution of a heterogeneous system requires more work. In this seminar, I will present the exchange of grains between wet and dry areas for very low liquid contents on the one hand and then for a local excess of liquid. I shall describe experiments of a flowing granular layer on top of wet substrates. I will emphasize the physical parameters that govern the phenomena : One surprise comes from the role of the velocity of the grains in the erosion process [Lefebvre et al 2016] as well in the growth of a wet aggregate [Saingier et al PRL 2017].

Artistic illustration of the impact of a grain on a wet aggregate. © G. Saingier





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