[Bruno Machado]

Hi all,

I am simulating a fuel cell in fluent through an model I built (UDF). Model seems to work fine, but there something is bothering me. In fluent manual, the sources of species and mass are said to be defined as, for example:

Sh2 = +0.3
So2 = 0.0
Sh2o = -0.1
4th species is N2, and it is not explicitly defined, as fluent solves (1 - N) for the last. in my case, it is 0.0.

So, for this, my source of mass should be

S_mass = Sh2 + So2 + Sh2o = 0.2

Nevertheless, I noticed that I have a large mass fraction of N2 in one of the sides of the fuel cell, despite the fact I am not supplying any at that side. Even in the domains I have no source term, there is Nitrogen.

Does anyone know the reason why this is happening? Or in case you faced this before, what have you done to solve it?

Thanks in advance.