title: Shear thickening and migration in granular suspensions.
abstract: We study the emergence of shear thickening in dense suspensions of non-Brownian particles. We combine local velocity and concentration measurements using magnetic resonance imaging with macroscopic rheometry experiments. In steady state, we observe that the material is heterogeneous, and we find that the local rheology presents a continuous transition at low shear rate from a viscous to a shear thickening, Bagnoldian, behavior with shear stresses proportional to the shear rate squared, as predicted by a scaling analysis. We show that the heterogeneity results from an unexpectedly fast migration of grains, which we attribute to the emergence of the Bagnoldian rheology. The migration process is observed to be accompanied by macroscopic transient discontinuous shear thickening, which is consequently not an intrinsic property of granular suspensions.
authors.affiliation: Université Paris Est, Laboratoire Navier (CNRS UMR 8205), Champs sur Marne, France.
authors.forename: Abdoulaye
authors.initials: A
authors.lastname: Fall
authors.forename: Anaël
authors.initials: A
authors.lastname: Lemaître
authors.forename: François
authors.initials: F
authors.lastname: Bertrand
authors.forename: Daniel
authors.initials: D
authors.lastname: Bonn
authors.forename: Guillaume
authors.initials: G
authors.lastname: Ovarlez
mesh_terms: D009038:Motion; D013314:Stress, Mechanical; D013535:Suspensions / Q000737:chemistry*; D019415:Torque; D014783:Viscosity
chemical_list: D013535:Suspensions