  We identify the sequence of microstructural changes that characterize the
evolution of an attractive particulate gel under flow and discuss their
implications on macroscopic rheology. Dissipative Particle Dynamics (DPD) is
used to monitor shear-driven evolution of a fabric tensor constructed from the
ensemble spatial configuration of individual attractive constituents within the
gel. By decomposing this tensor into isotropic and non-isotropic components we
show that the average coordination number correlates directly with the flow
curve of the shear stress vs. shear rate, consistent with theoretical
predictions for attractive systems. We show that the evolution in non-isotropic
local particle rearrangements are primarily responsible for stress overshoots
(strain-hardening) at the inception of steady shear flow and also lead, at
larger times and longer scales, to microstructural localization phenomena such
as shear banding flow-induced structure formation in the vorticity direction.
