The significance of coherent flow structures for the turbulent mixing ...
The significance of coherent flow structures for the turbulent mixing ...
The significance of coherent flow structures for the turbulent mixing ...
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7 Investigation <strong>of</strong> <strong>the</strong> yz-plane<br />
span-wise size <strong>of</strong> <strong>the</strong> high-speed <strong>flow</strong> <strong>structures</strong>, which reach <strong>the</strong> wall, is quite small with<br />
respect to <strong>the</strong> structure visible in <strong>the</strong> lower image. To examine <strong>structures</strong> which contribute to<br />
<strong>the</strong> <strong>turbulent</strong> <strong>mixing</strong> to a large extent, <strong>the</strong> Reynolds shear stress component was calculated <strong>for</strong><br />
each sample field and afterwards analysed if <strong>the</strong> intensity <strong>of</strong> this quantity was below a given<br />
threshold S Â <strong>of</strong> . It was already mentioned that <strong>the</strong> dominant <strong>structures</strong> with regard to <strong>the</strong><br />
magnitude <strong>of</strong> <strong>the</strong> Reynolds shear stress component appear quite seldom and do not contribute<br />
to <strong>the</strong> total production <strong>of</strong> turbulence to a large extent. However, as <strong>the</strong> structural features are<br />
500<br />
400<br />
Q4<br />
300<br />
y<br />
+<br />
200<br />
Q4<br />
Q4<br />
100<br />
Q2 Q2 Q2<br />
0<br />
0 100 200 300 400 500 600 700 800<br />
500<br />
y [???]<br />
x [???]<br />
400<br />
300<br />
y<br />
+<br />
Q4<br />
200<br />
100<br />
Q4<br />
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Q4<br />
0<br />
0 100 200 300 400 500 600 700 800<br />
z<br />
+<br />
y [???]<br />
x [???] 158<br />
FIGURE 7.20: Same as figure 7.18 but with strong production <strong>of</strong> turbulence (07583~ž ).
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