Combustion analysis using Roe's scheme and the Spalart--Allmaras model

The present work describes an efficient computational method for the simulation of turbulent flames. The main three ingredients of the method are Roe's schemes, the Spalart--Allmaras one-equation turbulence model, and a general preconditioning technique. These three ingredients are well known to ensure accuracy, robustness, and generality. The solution of the conservation equations is fully coupled, and the method is implemented in a three- dimensional parallel implicit solver. This potentially allows the use of the same mathematical method for the analysis of turbulent reactive flows at all speeds. The choice of the Spalart--Allmaras model, as opposed to typical two- equation models requires particular attention on the derivation of the micromixing time. Such a derivation is of fundamental importance, for the micromixing time represents the base upon which chemical source terms are built for many combustion models. Deriving a correct model for the micromixing time from the only resolved turbulent quantity kinematic eddy viscosity is challenging. To test the method, two low-Mach-number (0.1-0.2) turbulent reactive flows are simulated using the eddy dissipation model, and the results are compared with both experiments and previous numerical studies. It is established that the proposed method leads to satisfactory results. DOI: 10.2514/1.44331