Knudsen diffusion in channels and networks

The principal types of one-dimensional channels are the zig-zag channels and the connected cavities, and they have diffusivities that are much lower than the straight channels. The principal cause is lower vista which reduces the extreme lengths of the outlier rays, and the contributing causes are tortuosity, and negative correlation which increases the probability that consecutive steps are in opposite directions. The principal types of two-dimensional channels investigated are: rectangular, oblique, brick, hexagon, and straight-sinusoid or MFI type. They give rise to highly anisotropic diffusion tensors.