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