Coupling of particle ordering and stress fluctuations in shear thickening suspensions revealed by high speed confocal line scan imaging

Shear thickening suspensions transition from low viscosity to high viscosity or shear jammed states under high stress. While both the bulk rheology and the microscopic driving forces of such transitions are well-studied, the bridge between the microscopic and macroscopic scales is still unclear. Measurements at the boundaries indicate that dynamic high stress regions propagate through shear thickening suspensions of colloidal spheres. Here we use line scans on a confocal microscope to visualize high speed particle flows in a sheared suspension. These measurements reveal that high stress regions are correlated with significant drops in both speed and in local particle order, extending from the boundary many particle diameters deep into the suspension.