title: Macroscopic discontinuous shear thickening versus local shear jamming in cornstarch.
abstract: We study the emergence of discontinuous shear thickening (DST) in cornstarch by combining macroscopic rheometry with local magnetic resonance imaging measurements. We bring evidence that macroscopic DST is observed only when the flow separates into a low-density flowing and a high-density jammed region. In the shear-thickened steady state, the local rheology in the flowing region is not DST but, strikingly, is often shear thinning. Our data thus show that the stress jump measured during DST, in cornstarch, does not capture a secondary, high-viscosity branch of the local steady rheology but results from the existence of a shear jamming limit at volume fractions quite significantly below random close packing.
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: A
authors: A
authors: Fall
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: F
authors: F
authors: Bertrand
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: D
authors: D
authors: Hautemayou
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: C
authors: C
authors: Mezière
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: P
authors: P
authors: Moucheront
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: A
authors: A
authors: Lemaître
authors: Laboratoire Navier (UMR CNRS 8205), Université Paris Est, 77420 Champs-sur-Marne, France.
authors: G
authors: G
authors: Ovarlez