variable source on the interface
 

I am doing a fuel cell modeling by cfx 5.6. The mass source term at the each point should depend on the concentration of components at the corresponding point of the interface. The components will be consumed along the flow channel, so the source should also decline along the flow direction.

My question is how to express this variable source depending on I(X,Y) or concentration C(X,Y).

For example:

source term SH2=-1.[ kg kmol^-1 ]/F*Ia*100.[ mm^-1 ] Or total source term SH2=-1.[ kg kmol^-1 ]/F*areaInt(Ia)@catalystlayer

But I think that here I only introduce the volumtric averge source on the interface, how to correct it?

Expression Ia=I0a*(H2.molconc /conH2ref)^0.5*rate

100.[ mm^-1 ] represent the specific volume (i.e. the thickness of catalyst layer, which can be seen as a 2-D interface)

Thank you for your help.

Regards,

Yi Zhang