Figure 5.

Velocity v plotted against the number N of sites per cycle by keeping the entropy $\sigma$ per cycle and the diffusion coefficient D constant for $N\ge 3$. We chose the produced entropy per cycle to be $\sigma /k_B=5$. The red line is the value $v(N\to \infty )\to D\sigma /\pi R{k}_B$ in the limit of $N\to \infty$.