Improved shock-capturing methods for multicomponent and reacting flows

Existing shock-capturing schemes have difficulties with multispecies computations, creating nonphysical glitches at species interfaces. We attribute these glitches to inconsistencies in the equation of state in cells containing several species. Our remedy is to define mixtures within a grid cell as a collection of species which can possess distinct temperatures. This formulation requires solving an additional set of species energy equations. Computational results show that the glitches have been eliminated. For chemically reacting flow simulations, existing splitting methods often generate nonphysical waves at stiff reaction fronts. We show that this numerical phenomenon is due to the mixture model that overestimates the reaction temperature. This is avoided by introducing an enforcement on the reaction temperature that depends on the temperatures of each species. We demonstrate that the method computes detonation waves with time steps and grid sizes much larger than would be allowed to resolve reaction zones. (C) 1996 Academic Press, Inc.