The effective diffusivity of Brownian tracer particles confined in periodic micro-channels is
smaller than the microscopic diffusivity due to entropic trapping. Here, we study diffusion in
two-dimensional periodic channels whose cross section presents singular points, such as
abrupt changes of radius or the presence of thin walls, with openings, delimiting periodic
compartments composing the channel. Dispersion in such systems is analyzed using the
Fick-Jacobs (FJ) approximation. This approximation assumes a much faster equilibration in …