Rob
Ansys Employee

The species will enter the domain, (hopefully) react and leave. You only need to specify the fractions of reactants on the inlet, and I'd suggest some care on the outlet incase of reverse flow. Unless you're expecting intermediate species (CH3 radicals for example) on the inlet they'll have zero mass (mole) fraction. Fluent will calculate all of the combustion and therefore intermediate materials assuming you set it up.