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Accretion on wet granular materials

by Jop - published on , updated on

Accretion on wet granular materials

A new study combining experiments with modeling that predicts the growth of wet granular aggregates by addition of dry beads. This work was recently published in Physcial Review Letters.

Mixing a liquid with dry grains is the initial step of industrial processes resulting in granulation, construction materials, or health care products. As the first grains become wet, they form aggregates which more dry grains stick to, eventually producing a uniformly wet granular material. How does the wet aggregate grow? How are the dry grains collected by the surface of the wet aggregate?

To understand and optimize the interplay between the grains and the liquid, the team developed a model experiment, in which the pressure of the liquid in the wet saturated aggregate is finely tuned. This pressure determines the liquid fraction at the surface of the aggregate, which directly controls the capture of the grains. Accordingly the researchers show that the growth of the aggregate exhibits two different regimes, in which the dynamics is limited either by the fluid present at the surface or the number of particles impacting.

These findings may prove critical in optimizing industrial blending processes and in modeling geophysical events for instance during aeolian transport over a humid ground.

Contacts: Guillaume SAINGIER, Alban SAURET & Pierre JOP