Issue #119: CL pore-size expression (ESDLab/openfcst)

[AslanK]

New issue 119: CL pore-size expression
https://bitbucket.org/ESDLab/openfcst/issues/119/cl-pore-size-expression

Aslan Kosakian:

Mayank’s expression that allows for the estimation of the average Knudsen CL pore size based on the layer’s particle size and porosity needs to be implemented in OpenFCST so that the user doesn’t need to manually compute it. An option should be given for selecting a method for the Knudsen pore radius, either “Given” or “Sabharwal”. See Sabharwal et al., JES 2019.