is added to the left-hand side of the mass fraction equations. Here ρ is the fluid mixture density,
ωi is the mass fraction (dimensionless) of species
i, and
is the
pseudo time step. Since
ωi−nojac(
ωi) is always zero, this term does not affect the final solution. It does, however, affect the discrete equation system and effectively transforms a nonlinear iteration into a time step of size
.