Heterogeneities of complex fluids flows in model porous media
Orateur : Hugues Bodiguel
Laboratoire Rhéologie et Procédés, Grenoble
Résumé : When considering flows of non-Newtonian liquids in porous media, one expects a strong coupling between the non-linear properties of the liquids and the disorder of the solid structure. As a consequence, flow heterogeneities are usually enhanced, and it is not possible to derive directly effective Darcy laws from bulk rheological properties. I will consider in this talk a few types of systems, of increasing complexity ; using an experimental approach based on microfluidics channel networks, which is, when possible, compared to simple models and simulations. With polymer solutions, flow heterogeneities originates from the shear thinning behaviors of the solutions. However, when increasing the flow rates, elastic instabilities appear and tend to uniform the flow. With yield stress fluids, the flow depart significantly from that of a Newtonian liquid, as it concentrates in only a few preferential paths at high Bingham numbers. Although foams behave macroscopically like yield stress fluids, their flow properties are even more complex in a channel network. Indeed, foams in porous media are made of confined bubble or lamellae trains. Flow heterogeneities also appear at low capillary numbers, but for various reasons which are not linked bulk properties and which will be discussed.
Date et lieu : le Vendredi 29 Avril 2016 à 11h00, salle de séminaire IRPHE