Microstructural Evolution in Shear Thickening Fluids

Dense granular suspensions (e.g. concrete, foods and pharmaceuticals) can experience Discontinuous Shear Thickening (DST) in which a low-viscosity liquid transitions abruptly to a high-viscosity frustrated state characterised by frictional particle-particle contacts.

The steady state rheology is typically characterised by a flow curve that displays a flow reduction; a decreasing strain rate with increased stress.

However, the flow behaviour in this DST region (characterised by an 'S-shaped' flow curve) has baffled researchers and is still not understood.

The full S-shape predicted by prevailing theory is typically not observed in experiments which instead tend to display rapid fluctuations sometimes referred to as 'rheochaos'.

This project will use a combination of advanced rheometry, flow cell experiments, and simulations to reveal how the evolving microstructure of particle contacts interacts with the flow field to produce macroscale flow behaviour.

Recent results suggest that the unstable vs stable flow is controlled by the interplay between system inertia and microstructure evolution.