Mass fraction solutions
Mass fractions are computed in appSrc files YairEqn.H and YfuelEqn.H. For each specie other than the background “inert” specie, a partial differential equation is solved for Yair[i], where i is the specie index. The mass fraction of the “inert” specie is obtained by subtracting the sum of all the other species’ mass fractions from 1.