  Directed transport of interacting active (self-propelled)Brownian particles
is numerically investigated in confined geometries (entropic barriers). The
self-propelled velocity can break thermodynamical equilibrium and induce the
directed transport. It is found that the interaction between active particles
can greatly affect the ratchet transport. For attractive particles, on
increasing the interaction strength, the average velocity firstly decreases to
its minima, then increases, and finally decreases to zero. For repulsive
particles, when the interaction is very weak, there exists a critical
interaction at which the average velocity is minimal, nearly tends to zero,
however, for the strong interaction, the average velocity is independent of the
interaction.
