Behaviour of the current in a two-dimensional Büttiker－Landauer motor with entropic barriers

The behaviour of the current in a two-dimensional Büttiker--Landauer motor, which is a position-dependent temperature-driven Brownian motor, is investigated in the presence of entropic and energy barriers. It is found that the motion of the Brownian particles is influenced by the shape of the channel. The existence of an entropic barrier can cause an asymmetric current as the flatness ratio of the shape varies. There exists an optimized flatness ratio (nonzero) at which the current reaches its maximum value.