Stress Correlations in Shear Thickening Suspensions

In concentrated suspensions of neutrally buoyant particles, the apparent viscosity is often found to undergo an abrupt increase making a transition from a low-viscosity to a high-viscosity state, termed as discontinuous shear thickening (DST). The observed behavior has recently been linked to a transition from “lubricated” rheology, where close interactions between suspended particles take place through a thin liquid film, to a “frictional” rheology, where particles make unlubricated frictional contacts. Particle simulations that led to this concept have been successful in quantitatively reproducing the non-Newtonian behavior of thickening suspensions [1, 2]. We find that the system shows features of classical phase transition with the critical point being the volume fraction at which the derivative of the shear rate with respect to the shear stress becomes zero [3]. This point is associated with a pairing of solid fraction and friction coefficient, and respectively. The temporal and spatial correlations of the shear (and normal) stress at the critical point and their variation with the system size will be presented.

1. Seto et al. , Phys. Rev. Lett., 111(21), 218301, 2013.
2. Mari et al., J. Rheol. 58, 1693, 2014.
3. Singh et al., arXiv:1708.05749.