## Abstract

Perhaps the most important practical aspect of turbulent shear flows is their dominant effect on scalar fields such as temperature, density or chemical species. When turbulence exists, it tends to completely determine the mixing and diffusion of such quantities. Industrial flows with chemical reactions, combustion, and natural flows in the ocean and atmosphere usually involve turbulence constrained by forces, and complicated by factors, that laboratory studies often suppress; for example, stratification, rotation and shear. Unstratified, nonrotating, unsheared turbulence as described by the Batchelor (1967) classic book is so complex and poorly understood that many fluid dynamicists, and most undergraduate fluid mechanics textbooks, manage to avoid the subject completely. Papers in the present chapter on Scalar and Stratified flows confront many of the awkward uncertainties attending turbulence in the “real world”. Some excellent new tools exist today that were not available to Batchelor, and their impact is reflected in the following articles.

## Keywords

Internal Wave Stratify Flow Stratify Fluid Homogeneous Turbulence Turbulent Shear Flow## Preview

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