Numerical methods for treating disparate scales in high-speed reacting flows

Multiple length and time scales exist in high-speed reacting flows and need to be treated with due care when such flows are modeled. In this study, two numerical aspects relevant to reacting flow computations are addressed: (1) alternatively a fully implicit and a prediction-correction splining procedure for treating the stiff source terms arising in the chemically reacting flow field, and (2) a source term rescaling procedure to accommodate the disparate scales in the flow field. A shock-induced combustion scenario resulting from a hypersonic projectile flow is used as the test problem to facilitate investigation of these issues. It is found that the splining procedure can capture the coupling of the fluid dynamics and chemical reactions accurately, while reducing the computational requirements, and the rescaling treatment can compensate for the error caused by inadequate numerical resolutions.