Modeling of turbulent premixed flames using flamelet-generated manifolds

Efficient and reliable numerical models have become important tools in the design and optimization process of modern combustion equipment. For accurate predictions of flame stability and pollutant emissions, the use of detailed comprehensive chemical models is required. This accuracy, unfortunately, comes at a very high computational cost. The flamelet-generated manifold (FGM) method is a chemical reduction technique which lowers this burden drastically, but retains most of the accuracy of the comprehensive model. In this chapter, the theoretical background of FGM is briefly reviewed. Its application in simulations of premixed and partially premixed flames is explained. Extra attention is given to the modeling of preferential diffusion effects that arise in lean premixed methane–hydrogen–air flames. The effect of preferential diffusion on the burning velocity of stretched flames is investigated and it is shown how these effects can be included in the FGM method. The impact of preferential diffusion on flame structure and turbulent flame speed is analyzed in direct numerical simulations of premixed turbulent flames. Finally, the application of FGM in large-eddy simulations is briefly reviewed.