Macroscopic Discontinuous Shear Thickening vs 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 (MRI) 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 cornstach, 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.

To be published in PRL

References in corpus (3)

• Shear thickening of cornstarch suspensions as a re-entrant jamming transition
• Shear thickening and migration in granular suspensions
• Shear thickening of cornstarch suspensions

Cited by in corpus (4)

• Non-monotonic flow curves of shear thickening suspensions
• Mean-field microrheology of a very soft colloidal suspension: inertia induces shear-thickening
• Discontinuous Shear Thickening (DST) transition with spherical iron particles coated by adsorbed brush polymer
• Shear jamming and fragility in fractal suspensions under confinement