Order and density fluctuations near the boundary in sheared dense suspensions

We introduce a novel approach to reveal ordering fluctuations in sheared dense suspensions, using line scanning combined rheometer and laser confocal microscope. validate the technique with moderately suspension, observing modest shear-induced nearly linear flow profile. At high concentration ( ϕ = 0.55) applied stress just below shear thickening, we report temporal resolution, directly measure decrease order distance from suspension’s bottom boundary as well direct correlation between particle concentration. Higher produces thickening large which find are accompanied by dramatic suspension speeds. The peak rates independent of boundary, indicating that they likely arise transient jamming creates solid-like aggregates particles moving together, but only briefly because speed interspersed regions flowing much more slowly, suggesting suspensions possess complex internal structural dynamics, even relatively simple geometries.