  Rectification of interacting Brownian particles is investigated in a
two-dimensional asymmetric channel in the presence of an external periodic
driving force. The periodic driving force can break the thermodynamic
equilibrium and induces rectification of particles (or finite average
velocity). The spatial variation in the shape of the channel leads to entropic
barriers, which indeed control the rectification of particles. We find that by
simply tunning the driving frequency, driving amplitude, and shape of the
asymmetric channel, the average velocity can be reversed. Moreover, a short
range interaction force between the particles further enhances the
rectification of particles greatly. This interaction force is modeled as the
lubrication interaction. Interestingly, it is observed that there exists a
characteristic critical frequency $\Omega_c$ below which the rectification of
particles greatly enhances in the positive direction with increasing the
interaction strength; whereas, for the frequency above this critical value, it
greatly enhances in the negative direction with increasing the interaction
strength. Further, there exists an optimal value of the asymmetric parameter of
the channel for which the rectification of interacting particles is maximum.
These findings are useful in sorting out the particles and understanding the
diffusive behavior of small particles or molecules in microfluidic channels,
membrane pores, etc.
