The standard mixture fraction/reaction progress model assumes a two-stream mixing process of fuel and oxidizer. The residual material model extends this framework by mixing with a third stream, the residual or ballast material. The global mixing and reaction scheme is:
 | (7–83) |
The residual material does not participate in the combustion directly, but it does interact with the mixture and the propagation of the flame. The most significant effects are:
Lower peak temperature (dilution)
Slow down in laminar burning velocity
Different mixture composition in chemical equilibrium because of lower temperature level and chemical interaction of residual with products
For the dependency of the laminar burning velocity on the residual material concentration see also section Equivalence Ratio Correlation.