The destruction of temperature fluctuations in a turbulent plane jet

Abstract

The transport equation for the destruction of temperature fluctuations in a turbulent shear flow is briefly discussed from the point of view of the experimenter's ability to measure the important terms. The transport equation for only one component of the destruction, the mean-square streamwise temperature derivative, is considered in detail in the case of a steady two-dimensional turbulent shear flow. Measurements of most of the terms in this equation have been made in the self-preserving region of a turbulent plane jet. They indicate that the advection and diffusion terms are negligible compared with the production and dissipation terms. The measured terms are discussed in the context of local isotropy. Mean-square values of second-order derivatives satisfy local isotropy more closely than those of first-order derivatives.