  The shear-induced self-organization of active rotors into stripy aggregates
is studied by carrying out computational simulations. The rotors, modeled by
monolayers of frictional spheres, develop to stripy microstructures only when
they counterrotate with respect to the vorticity of the imposed shear flow. The
average width of the stripes is demonstrated to be linearly dependent on the
relative intensity of active torque to the shear rate. By giving insight into
three collective particle behaviors, i.e., shear-induced diffusion,
rotation-induced rearrangement, and edge flows, we explain the mechanisms of
formation of the particle stripes. Additionally, the rheological result shows
the dependence of shear and rotational viscosities on the active torque
direction and the oddness of the normal stress response. By exhibiting a
collective phenomenon of active rotors, our study paves the way to
understanding chiral active matter.
