  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.
