PEM modeling UDS diffusivity in mixture

gemini

Hi,

I am modeling PEM fuel cell using UDFs. For the definition UDS diffusivity (e.g. electric potential ) I wrote a UDF that assign different diffusivity values for different zones of fuel cell. In meterials panel for solid materials I hook this UDF succesfully and it works. But it does not work correctly for porous fluid zones such as gdl catalyst layer and flow channels. Is there any way to assign very small diffusivity for specified porous zones. I tried mixture UDS diffusivity definition in material panel however when I start iteration solution diverges.

Also, is FLUENT use solid material UDS diffusivity value or fluid mixture UDS diffusivity for solving a UDS in porous zones?

have a nice day...