Comparison of subfilter scale models for LES of turbulent premixed flames

The role of subfilter scale models for representing turbulence-chemistry interactions in large eddy simulations (LES) of turbulent premixed combustion is of considerable impor- tance as the internal structure of premixed flames is generally smaller than the filter sizes. Moreover, the accuracy and validity of LES subfilter scale models for premixed combustion are still under debate. A detailed comparison is made between two laminar flamelet type modeling approaches: one approach based on the thickened flame and power-law flame wrinkling models and a second approach based on the flame surface density (FSD) model. The strengths and limitations of both methods are examined and the numerical predictions of the thickened flame and FSD models are investigated and compared for freely propagating premixed flames. The numerical results also include a discussion of the influence of turbulence intensity on the turbulent flame speed and flame structure. The study is intended to provide insight into the computational and physical modeling requirements for performing LES of turbulent premixed flames.