[lyyl]

I am doing the pem simulation using fluent udf .I have some questions to ask everyone.
Firstly, I want to know how to determine the reference current density(A/m2),which need to enter in pem panel. many kinds of literature just give volume reference exchange current density (A/m3)
Secondly, in the material panel, the uds diffusivity of the current collector needs to be changed to cond: fuelcells, or keep the default？how to set fc-mixture,does the cp of the gas is fixed?
thirdly,in the boundary conditions,When I set the wall-terminal temperature boundary conditions, I found that the name of the material is aluminum, Do I need to change this to collect-default?
last,I don't konw how to get the current density，is it anode current density plus cathode current density,or the integral of current density on the Y-direction surface.I found that their values are different.
can you help me? Thanks a lot.