  Diffusion and rectification of Brownian particles powered by a rotating wheel
are numerically investigated in a two-dimensional channel. The nonequilibrium
driving comes from the rotating wheel, which can break thermodynamical
equilibrium and induce the directed transport in an asymmetric potential. It is
found that the direction of the transport along the potential is determined by
the asymmetry of the potential and the position of the wheel. The average
velocity is a peaked function of the angular speed (or the diffusion
coefficient) and the position of the peak shifts to large angular speed(or
diffusion coefficient) when the diffusion coefficient (or the angular speed)
increases. There exists an optimal angular speed (or diffusion coefficient) at
which the effective diffusion coefficient takes its maximal value. Remarkably,
the giant acceleration of diffusion is observed by suitably adjusting the
system parameters. The parameters corresponding to the maximum effective
diffusion coefficient are not the same as the parameters at which average
velocity is maximum.
