Linear-eddy modelling of turbulent transport. Part 7. Finite-rate chemistry and multi-stream mixing

Abstract

The linear-eddy turbulent mixing model, formulated to capture the distinct influences of turbulent convection and molecular transport on turbulent mixing of diffusive scalars, is applied to two mixing configurations in homogeneous flow: a scalar mixing layer and a two-line-source configuration. Finite-rate second-order chemical reactions are considered, as well as the limits of fast reaction and frozen flow. Computed results are compared to measurements in a reacting-scalar mixing layer and in a two-line-source configuration involving passive-scalar mixing. For each configuration, the adjustment of a single model parameter related to the turbulence integral scale yields computed results in good agreement with a variety of measured quantities. The results are interpreted with reference to a simpler model, based solely on large-scale flapping effects, that reproduces many qualitative trends. For three-stream mixing with finite-rate chemistry, a novel dependence of the reactant correlation coefficient on the chemical reaction rate is predicted.