Numerical Simulation of Turbulent Flames based on a Hybrid RANS/Transported-PDF Method and REDIM Method

A hybrid RANS/Transported-PDF model for the simulation of turbulent reacting flows based on automatically reduced mechanisms for the chemical kinetics (reaction-diffusion manifold, REDIM) is presented in this work. For modelling of turbulent reacting flows, chemistry is a key problem and affects largely the accuracy. The PDF method has been widely used since the chemical source term is in a closed form, without any modelling. Despite of this advantage of PDF method, detailed chemical kinetics is not desired due to its heavy computational effort. From this aspect, the detailed chemical kinetics is simplified by the reaction-diffusion manifold (REDIM) method. The hybrid RANS/Transported-PDF model based on REDIM reduced kinetics is applied to simulate the Sandia piloted Flame E, which has a moderate degree of local extinction. The numerical results are validated through comparison with experimental data and show good qualitative and quantitative agreements.