Unbiased Diffusion through a Linear Porous Media with Periodic Entropy Barriers: A Tube Formed by Contacting Ellipses

Figure 1

Elliptic tube. (a) A tube of circular cross-section where the position-dependent radius is given by , an ellipse in the longitudinal plane, as shown in (b), where is the square of its major radius. is the size of the minor radius of the elliptic shape; the tube’s length is , where . The radius of the openings, at opposing sides of the tube, is , else , where . Panel (c) shows a representation of the entropic-like potential associated with the change of shape in this tube.

(a)

(b)

(c)