On local isotropy of small scale temperature fluctuations
Abstract
The measured skewness of the streamwise temperature derivative in both laboratory and atmospheric turbulent flows in earlier studies has been found to be nonzero and of either sign, and essentially independent of Reynolds number, for a sufficiently large Re value. The paper examines the apparent contradiction of this result with the hypothesis of local isotropy, in the context of evidence for the presence of a highly organized largescale motion in turbulent shear flows. Only nonsymmetrical bulges of selected durations are considered, where bulges are simply excursions in the temperature trace above the ambient level. It is shown that the statistical properties of the subset of smallscale fluctuations are consistent with the requirements of local isotropy. In particular, the skewness of smallscale fluctuations is found to be negligible in comparison with that of the largescale motion.
 Publication:

6th International Heat Transfer Conference, Volume 5
 Pub Date:
 1978
 Bibcode:
 1978iht.....5..359S
 Keywords:

 Atmospheric Temperature;
 Isotropic Turbulence;
 Turbulent Flow;
 Probability Density Functions;
 Reynolds Number;
 Skewness;
 Fluid Mechanics and Heat Transfer