Negative pressure in shear thickening band of a dilatant fluid

TL;DR

This study combines experiments and simulations to reveal that negative pressure within shear thickening bands in dilatant fluids is a key factor in the shear thickening mechanism, driven by Reynolds dilatancy and contact structure formation.

Contribution

It demonstrates that negative pressure occurs in shear thickening bands and links dilatancy to the solidification process in dilatant fluids, supported by experimental and numerical evidence.

Findings

Negative pressure is present in shear thickening bands.

Dilatancy causes negative pressure leading to solidification.

Shear thickening oscillations occur around 20 Hz.

Abstract

We perform experiments and numerical simulations to investigate spatial distribution of pressure in a sheared dilatant fluid of the Taylor-Couette flow under a constant external shear stress. In a certain range of shear stress, the flow undergoes the shear thickening oscillation around 20 Hz. We find that, during the oscillation, a localized thickened band rotates around the axis with the flow. {Based upon experiments and numerical simulations, we show that a major part of the thickened band is under negative pressure even in the case of discontinuous shear thickening}, which indicates that the thickening is caused by Reynolds dilatancy; the dilatancy causes the negative pressure in interstitial fluid, which generates contact structure in the granular medium., then frictional resistance hinders rearrangement of the structure and solidifies the medium.