Implementation of the thickened flame model for large eddy simulation of turbulent premixed combustion in a commercial solver

The Thickened Flame model of Colin et al. for Large Eddy Simulation of turbulent premixed combustion has been implemented in a general purpose, commercial CFD solver. In this model, the computation of the filtered reaction rate involves a third order derivative operator acting on the velocity field. The evaluation of this operator is non-trivial even for cartesian grids, and indeed quite difficult for unstructured grids. Strategies to overcome these difficulties are discussed in the paper; in order to ease the implementation for unstructured grids in a commercial solver, a slight modification of the original thickened flame model is proposed. Both the original and the modified version of the thickened flame model are validated against experimental data (velocity distribution and flame position) for a turbulent, bluff-body stabilized, premix flame. A comparison against results obtained with the Turbulent Flame speed Closure LES-model proposed by Flohr and Pitsch is also presented.