Vortex simulation of a three-dimensional reacting shear layer with infinite-rate kinetics

The three-dimensional transport element method is extended to solve the conservation equations for reacting flow. The numerical scheme belongs to an adaptive, Lagrangian class of field methods in which computational effort is concentrated in zones of finite vorticity and chemical reaction. We use the low Mach number approximation of combustion and restrict our attention to the case of diffusion flames with no heat release. A singlestep, second-order, infinite-rate kinetics chemical reaction model is employed. The scheme is applied to study the effect of flow-induced instabilities on the reaction field in a temporal shear layer. Results are obtained in the high Peclet number regime for a wide range of Damkohler numbers. Changes in the reaction field are related to either the entrainment or the strain field associated with the saturation of the instabilities. With increasing Damkohler number, the reaction region changes from a distributed zone embedded within spanwise and streamwise vortices to a thin sheet surrounding their cores. The product concentration always exhibits strong similarity to the vorticity distribution, realizing its highest values in zones of high vorticity and falling rapidly in regions where the vorticity is small. Variation of the Peclet number yields minor changes in the product distribution and in the reaction zone structure, but strongly affects product formation rates.