HEAT TRANSFER AND TURBULENT MMING LAYERS
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7. CHARACTERISTICS OF THE TEMPERATURE FIELD
IN THE TUR~ULENT REGIME
Figure 13 shows a smoke photograph of the flow exhibiting clearly the
intermittent front at its low velocity side.
FIG. 13. Smoke photograph of shear layer.
7.1. The lntermittency Distribution
The statistics of this front is described by the intermittency factory which
is plotted in Fig. 14. Since in these measurements the 6 signal was obtained
directly, conditional averages of the temperature characteristics could also
be obtained.
7.2. The Mean Temperature in the Turbulent and Nonturbulent Regions
These measurements are presented in Fig. 15. The mean temperature distribution in the turbulent zone is rather flat and homogeneous, which is in
contrast to the mean velocity characteristic (Wygnanski and Fielder, 1970).
7.3. The Variance of the Temperature Fluctuation
In measuring the mean variance of the temperature fluctuation one has to
consider the fact that the mean values of the temperature in the two zones of
the flow are different from each other and different from AT. In defining the
variance in the turbulent zone as z / A T A , where jg T i 6(t) dt = 0 we have