The permeability operation is available for all versions of PoreXpert.

 

The permeability algorithm calculates the network permeability for any of the liquids or gases in the materials database. The permeability is calculated in milliDarcy units, the conversion from milliDarcy units to SI units is detailed in the Units topic earlier in the help documentation. The values are different because of slip/Knudsen flow of molecules of gases (i.e. the molecules can bounce their way through). The effect is most noticeable, relative to laminar / Poiseuillian flow, for small molecules in low density gases passing through narrow throats. The difference between the nitrogen and liquid permeability corresponds to the Klinkenberg effect.

 

The network permeability is related to the absolute permeability of the structure. For the geometric structure as drawn, over a small throat size range, the absolute permeability in milliDarcy units is equal to the network permeability. For larger throat size ranges, and more occluded samples, the network permeability increasingly underestimates the absolute permeability in small unit cells. Larger unit cells provide more realistic values of permeability and are more stable when changing between stochastic realisations.

 

The next figure shows the permeability screen in PoreXpert.

 

Permability screen in PoreXpert

 

Note:

This operation may take a very long time to complete, depending on your hardware capabilities and the unit cell size. The amount of ram available on your system will restrict the largest unit cell size, that your system can calculate.