Multi-component diffusion in 2-dimensional laminar methane/air flames

Numerical simulations are performed of a two-dimensional, laminar, atmospheric pressure methane/air flame on a slit burner. A relatively detailed mechanism, consisting of 25 reactions between 16 species, is used to model the combustion chemistry. The transport phenomena are modelled through the Maxwell-Stefan equations, to fully account for the multicomponent nature of the gas mixture and thermal diffusion effects. The results are compared to those obtained with a more simple transport model, based on Fick's law, which is commonly used in laminar flame modelling. The differences between the two models are clear, but relatively small. Compared to the simple model, the full transport model predicts an 8% larger flame length, a 4% larger flame sheet thickness, and a 5K lower maximum flame temperature.