A posteriori tests of a dynamic thickened flame model for large eddy simulations of turbulent premixed combustion

Abstract

Dynamic models where model parameters are automatically adjusted from known resolved fields are a very attractive formulation for large eddy simulations. Now widely used for unresolved momentum transport, this approach remains rather marginal to describe filtered reaction rates despite of very promising results. Global and local dynamic formulations for the flame wrinkling factor are combined with the Thickened Flame (TFLES) model to simulate the F3 pilot stabilized jet flame studied experimentally by Chen and coworkers. The influence of physical (flame wrinkling inner cut-off length scale) and numerical (test filter width, averaging procedure, updating frequency) characteristics of a flame wrinkling factor dynamic model for turbulent premixed combustion is investigated. Numerical results are discussed in terms of mean flow fields as well as dynamical behaviors. It is shown that the dynamic model is robust and relatively insensitive to the numerical input coefficients to be provided beforehand in the code. This finding indicates that the model parameter does not need to be adjusted any more. However, a model for the inner cut-off scale of flame wrinkles, lost in the filtering process, is required.