  Directed transport of self-propelled particles is numerically investigated in
a three-dimensional asymmetric potential. Beside the steric repulsive forces,
hydrodynamic interactions between particles have been taken into account in an
approximate way. From numerical simulations, we find that hydrodynamic
interactions can strongly affect the rectified transport of self-propelled
particles. Hydrodynamic interactions enhance the performance of the rectified
transport when particles can easily pass across the barrier of the potential,
and reduce the rectified transport when particles are mainly trapped in the
potential well.
