Application of Hybrid Transported-Tabulated Chemistry for Efficient Large-Eddy Simulation of Turbulent Combustion

Abstract The performance of a hybrid transported-tabulated chemistry (HTTC) strategy is evaluated for large-eddy simulations (LES) of turbulent combustion with detailed finite-rate kinetics. The computational cost of LES is reduced in the HTTC approach by segregating the species list into major and minor species, with the former transported and the latter tabulated. Apart from reducing the number of transported species, the HTTC approach and its variants decrease computational cost by enabling efficient computation of thermodynamics and transport properties and by relieving the stiffness of chemical source terms. The calculations can be up to 11 times faster with stiff kinetics (29 species, 141 steps), as the HTTC approach eliminates the need to integrate and transport the minor species, which typically have short chemical times. The original HTTC and other variants are assessed for their accuracy, efficiency, and robustness for LES by considering two temporally evolving challenging test cases: a freely propagating turbulent premixed flame in the thin reaction zone regime and a turbulent non-premixed jet flame exhibiting local extinction and re-ignition. Modifications to the original HTTC approach are considered and evaluated to account for the effect of subgrid-scale turbulence. Both a priori and a posteriori analyses are conducted to evaluate the accuracy of the HTTC approach. The turbulent premixed flame test shows noticeable yet small differences between the calculated and tabulated concentrations of minor species. This results in reasonable predictions of reaction rates and overall combustion process with HTTC. The difference between calculated and tabulated minor species concentrations is larger for the turbulent non-premixed flame case; however, the minor species concentrations are generally much lower for it, and therefore, extinction-re-ignition physics is still predicted well with HTTC.