Figure 1.

(a) Schematic representation of the tube formed by spherical compartments. (b) Effective mobility and (c) diffusion coefficient of a point particle in such a tube found in Brownian dynamics simulations at ν=a∕R=0.3 $\left(l∕R=2\sqrt{1-{\nu }^2}\approx 1.91\right)$ are shown by squares and circles, respectively, while triangles in panel (b) show function w(F), Eq. 7. Dashed lines represent asymptotic behaviors of the corresponding quantities. μ_eff and D_eff were calculated by mapping motion of the particle onto the random walk among the openings and using the formulas for μ_eff and D_eff derived in Ref. 13. The results were obtained by averaging over 2.5×10⁴ transitions among the openings. If the trajectory crossed the compartment wall, the step was rejected. The dimensionless time step $\Delta \tilde{t}=D\Delta t∕R^2$ was different at different values of the driving force: $\Delta \tilde{t}={10}^{-6}$ at βFR≤1, $\Delta \tilde{t}={10}^{-6}∕\left(\beta FR\right)$ at βFR≥1. The error in our numerical results is smaller than the size of the symbols in the figure.