Non-monotonic flow curves of shear thickening suspensions

Abstract

The discontinuous shear thickening (DST) of dense suspensions is a remarkable phenomenon in which the viscosity can increase by several orders of magnitude at a critical shear rate. It has the appearance of a first order phase transition between two hypothetical "states" that we have recently identified as Stokes flows with lubricated or frictional contacts, respectively. Here we extend the analogy further by means of novel stress-controlled simulations and show the existence of a non-monotonic steady-state flow curve analogous to a non-monotonic equation of state. While we associate DST with an S-shaped flow curve, at volume fractions above the shear jamming transition the frictional state loses flowability and the flow curve reduces to an arch, permitting the system to flow only at small stresses. Whereas a thermodynamic transition leads to phase separation in the coexistence region, we observe a uniform shear flow all along the thickening transition. A stability analysis suggests that uniform shear may be mechanically stable for the small Reynolds numbers and system sizes in a rheometer.

v2: typos corrected + various text improvements, 6 pages, 5 figures

References in corpus (2)

• Shear thickening of cornstarch suspensions as a re-entrant jamming transition
• Macroscopic Discontinuous Shear Thickening vs Local Shear Jamming in Cornstarch

Cited by in corpus (4)

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• Shear thickening of suspensions of dimeric particles
• The role of microscopic friction in statistics and scaling laws of avalanches
• Implicit type constitutive relations for elastic solids and their use in the development of mathematical models for viscoelastic fluids