Porosity
 

Guys,

I've been working with the simulation of a fuel cell channel. I want my mass diffusivity coefficient to be corrected by the porosity and the fraction of liquid water as it follows:

D_eff= D_i * (por * (1 - s))**1.5

The following piece of code is how I defined my porosity profile as a function of POROSITY(t) and C_LIQ_H2O(c,t) (porosity and fraction of liquid water, respectively).

DEFINE_PROFILE(porosity,t,i)
{
cell_t c;

begin_c_loop(c,t)
{
C_PROFILE(c,t,i) = POROSITY(t)*(1.0-MIN(MAX(C_LIQ_H2O(c,t),0.0),0.99));
}
end_c_loop(c,t)
}

I read once in the manual that the mass diffusivity is automatically corrected by the porosity (profile), thus to correct it by the factor of 1.5, should I multiply the diffusivity (D_i) by the porosity macro (C_POR(c,t)) on the power of 0.5 only?

D_eff= D_i * C_POR(c,t)**0.5

Despite the fact I read it once in the manual, unfortunately, I could not find this information again. It would be great if you could inform where I can find it.

Thanks guys.

Any one can help me?

Dear MAchado
You can find the information in the "pem_user.c"