Structure of temperature fluctuations in a turbulent boundary layer

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Abstract
Statistics of temperature fluctuations are measured in a slightly heated boundary layer well downstream of a step change in wall heat flux. Measurements include probability density functions and spectra of temperature ϑ and of its time derivative ∂ϑ/∂t, and distributions of the skewness and flatness factors of ϑ and ∂ϑ/∂t. These results are compared with existing data for the velocity and its time derivative. The Reynolds number dependence of high order moments of ∂ϑ/∂t is in qualitative agreement with that obtained by Frenkiel and Klebanoff for velocity derivative data. Spectra of (∂ϑ/∂t)2 exhibit a power law behavior both in the viscous sublayer and in the outer region of the layer, but the exponent is different in the two regions.