  Using a novel approximation scheme within the convective diffusion (two body
Smoluchowski) equation framework, we unveil the shear-driven aggregation
mechanism at the origin of structure-formation in sheared colloidal systems.
The theory, verified against numerics and experiments, explains the induction
time followed by explosive (irreversible) rise of viscosity observed in
charge-stabilized colloidal and protein systems under steady shear. The
Arrhenius-type equation with shear derived here, extending Kramers theory in
the presence of shear, is the first analytical result clearly showing the
important role of shear-drive in activated-rate processes as they are
encountered in soft condensed matter.
