Closures for multicomponent reacting flows based on dispersion analysis

Using ideas drawn from the analysis of a single nonreacting scalar in the context of Taylor dispersion, we derive formulas for closures for the mean state of a turbulent binary reacting system. These nonlinear expressions, derived in the context of a simplified sandbox problem, explicitly show the effects of reaction parameters on unresolved transport. When translated to a turbulent flow setup, the resulting models provide improved predictions of mean scalar quantities and showcase some limits to purely local modeling.