{"id":13632,"date":"2021-02-03T14:03:44","date_gmt":"2021-02-03T13:03:44","guid":{"rendered":"https:\/\/navier-lab.fr\/?page_id=13632"},"modified":"2024-08-01T15:51:36","modified_gmt":"2024-08-01T13:51:36","slug":"granular-and-particulate-media","status":"publish","type":"page","link":"https:\/\/navier-lab.fr\/en\/research\/rheophysics-porous-media\/granular-and-particulate-media\/","title":{"rendered":"Granular and Particulate Media"},"content":{"rendered":"

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We conduct research on dense granular material rheology — notably wet and unsaturated media — and we also investigate their acoustic properties. We use inclined planes, rheometers and more recently a rotating cell allowing us to trigger avalanches in quasistatic conditions. We also study these materials through numerical simulations with over twenty years of experience in the domain.<\/p>\n

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Unsaturated wet granular materials<\/h2>Read More<\/a><\/div>\n <\/article><\/div><\/div>
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Acoustic wave diffusion in immersed granular media<\/h2>Read More<\/a><\/div>\n <\/article><\/div><\/div>
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Structure and Rheology of Wet, Unsaturated Granular Media<\/h3>\n

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A. Fall, J.-N. Roux, F. Chevoir, A. Awdi (PhD), C. Chateau (ME)<\/h5>\n
Collaborations : S. Deb\u0153uf (d’Alembert)<\/h5>\n

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\nExperiments on the rheology of granular materials wetted by a silicone oil are in good agreement with discrete element<\/em> numerical simulations conducted in-house. Both follow rheological models of \u00b5<\/em>(I<\/em>)-type, generalised to include a characteristic pressure P*<\/sup><\/em> defined as :<\/p>\n

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\nWith P<\/em> the confinement pressure, d<\/em> the grain diameter and F0<\/sub> <\/em>the inter-granular, attractive force (here proportional to the surface tension). More recently, the experimental study of the rheology of these materials has been extended to inclined plane experiments in collaboration with S. Deboeuf from Institut Jean le Rond d’Alembert.<\/em> The micromorphology of these materials is observed by Discrete Element method in numerical simulations and by X-ray microtomography in a tailor-made experimental setup allowing us to measure the microstructure dynamics.<\/p>\n

We have used advanced image segmentation algorithms leveraging Articifial Intelligence tools to precisely analyse the microstructure (grain arrangement, liquid bridge morphology evolution under shear) that can go beyond the pendular regime of isolated liquid bridges (PhD thesis of Ahmad Awdi, co-supervised with C. Chateau of the Multi-\u00c9chelle group). Another recent development is the study of the viscous effects in these liquid bridges for steady shear and large amplitude oscillatory shear (LAOS). The rheological properties of these systems are then characterised by a visco-inertial number J <\/em>combining the classical inertial number I <\/em>from granular matter rheology and the viscous number Iv <\/sub><\/em>characteristic of suspensions in the Stokes regime :<\/p>\n

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Measuring the water content in an insaturated granular material using X-ray microtomography. (a) Microtomograph and the in-place experimental setup (b) Cross-sectional view of the shear cell. (c) Translation and rotation stage at the bottom of the shear cell, hidden from view in Panel (a).
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Water content in a slice of an unsaturated wet granular material (left) in the initial state (right) after 10 minutes under shear.
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Simple liquid bridges and more complex morphologies between particle pairs (triplets, quadruplets, …) of unsaturated wet granular materials.
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References<\/h4>\n