Properties such as electrolyte phase electrical conductivity, water diffusivity, and the osmotic drag coefficient are evaluated as functions of the water content, using various correlations as suggested by [8] (p. 79). To capture the relevant physics of the problem, various properties of the membrane are incorporated into the model as default options. You can, however, directly incorporate your own formulations and data for these properties by editing the functions defined in the provided source code file called pem_user.c and compiling the code yourself. For more information, see User-Accessible Functions (p. 39).