A filtered flame approach for simulation of unsteady laminar premixed flames

The simulation of laminar flames consists of capturing the evolution of a very large number of species that may react within a broad range of time scales. It results in a highly non-linear stiff numerical problem that requires large computational resources. In the present paper, an alternative approach for the simulation of unsteady premixed flames is proposed. The approach focuses on describing the flame using a single scalar only (so-called progress variable) on relatively coarse grids. The unresolved details of the flame structure are analysed and described in term of spatial filtering. A model originally developed for large eddy simulation is discussed in the framework of unsteady laminar flames. The ability of the present approach to represent the filtered flame structure is validated against detailed numerical simulations of freely propagating laminar flames. Further, simulations of steady and unsteady laminar Bunsen flames are presented with a focus on the influence of the numerical grid and filter width upon the flame dynamics.