Flow density of a reversible ratchet.

By defining "flow density" in a reversible ratchet, a kind of Brownian motor that runs four processes in a two-dimensional parameter space to complete a cycle, we analytically investigate the behavior of the motor's integrated flow in terms of the magnitude and location of the density maximum. It turns out that flow density gives information that can serve as a guide for obtaining the most suitable integrated flow important in the design of reversible ratchets.