  Using numerical simulations, we examine the dynamics of driven
two-dimensional bidisperse disks flowing over quenched disorder. The system
exhibits a series of distinct dynamical phases as a function of applied driving
force and packing fraction including a phase separated state as well as a
smectic state with liquid like or polycrystalline features. At low driving
forces, we find a clogged phase with an isotropic density distribution, while
at intermediate driving forces the disks separate into bands of high and low
density with either liquid like or polycrystalline structure in the high
density bands. In addition to the density phase separation, we find that in
some cases there is a fractionation of the disk species, particularly when the
disk size ratio is large. The species phase separated regimes form a variety of
patterns such as large disks separated by chains of smaller disks. Our results
show that the formation of laning states can be enhanced by tuning the ratio of
disk radius of the two species, due to the clumping of small disks in the
interstitial regions between the large disks.
