Multiple mapping conditioning coupled with an artificially thickened flame model for turbulent premixed combustion

A hybrid Euler/Lagrange approach is introduced for the simulation of turbulent stratified flames. Large eddy simulations (LES) are used for the simulation of the flow field while artificial thickening of the flame provides sufficient resolution for the computation of the evolution of the filtered reaction progress variable. This model is complemented by a sparse Lagrangian particle method that provides instantaneous and local solutions of the species composition and can account for deviations from the flamelet-structure due to turbulence. The combined approach provides a model applicable to different premixed flame regimes including the corrugated and thickened flame regimes. The particle mixing model is based on a multiple mapping conditioning (MMC) approach that conditions mixing on a reference field (the reaction progress variable). Thus, the model ensures localness of mixing in composition space and prevents unphysical mixing of unburnt fluid with burnt fluid across the flame front. The MMC-LES results show good agreement with experimental data, and flamelet-like structures as well as deviations thereof can be predicted. The results are rather insensitive towards the MMC specific modelling parameters but the modelling of the mixing time scale needs to be adapted to achieve consistency between the flame propagation speed predicted by the artificially thickened flame model and the flame dynamics predicted by MMC.