Tuning the Shear Thickening Response using Acoustic Perturbations

Shear thickening behavior of dense particle suspensions is generally not considered an externally tunable response. In this work, we present a novel method to dynamically tune the rheological response of a non-Brownian shear thickening suspension using local acoustic perturbations. We apply resonant perturbations in two different directions orthogonal to the primary shear flow and show a tunable viscosity response of the suspension in the transitioning regime and the shear-thickened regime of the flow curve. We find that the acoustic perturbations increase the onset strain rate of shear thickening in addition to decreasing the viscosity (de-thickening) of the suspension. We attribute the mechanism of de-thickening to the breaking of shear-induced force chains and disruption of solid-solid frictional contact between the particles by local acoustic perturbations. With the temporal amplitude modulation of the perturbations, we further demonstrate a periodic thickening/de-thickening of the suspension and show that the response is dynamically tunable.