Molecular Mixing and Chemical Reactions in Turbulent Shear Flows

The general topic of this chapter is molecular mixing and chemical reaction in turbulent shear flow, in particular, in two-dimensional mixing layers and axi-symmetric jets. The discussion is centered around recent experiments in these two flows and upon proposed new interpretations of the observations. The central issue is the nature of the pathway from the freestream to the molecularly mixed state. The experimental results suggest that the path does not resemble that given by turbulent diffusion concepts. They imply, as well, that molecular transport coefficients influence molecular mixing rates even in what are conventionally called fully-developed turbulent flows. In the proposed model, this influence is felt at the Taylor scale.