[mturcios777]

I think Cp is one of those that needs to be calculated from your mixture. You might need to do something like this (this is rough pseudocode ).

fvPatchField<scalarField> Cp = 0;
forAll(Y,specI)
{
    Cp+=Y[speci].thePatchFieldYouWant*Cp.listOfSpecies[index for specI]
}

I think Cp lives in thermo somewhere, but I'm not 100% sure. Maybe look up a BC for alpha or alphat, as I think that would have access to what you need.