  Incommensurate easy flow channels in an otherwise perfect vortex lattice are
investigated. The associated (point) defects in the lattice inside the channel
cause an almost vanishing critical current, as shown by molecular dynamics
simulations and a comparison with the Frenkel-Kontorova model. In addition to
the normal flux flow behavior we find a low mobility regime at small drives
associated with defect motion. We treat this situation analytically for the
case of a single defective vortex row. We also briefly discuss the relation to
existing experiments on artificial vortex channels.
