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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7.5 Properties <strong>of</strong> <strong>coherent</strong> velocity <strong>structures</strong><br />
7.5.2 Sweeps<br />
In order to interprete <strong>the</strong> results from <strong>the</strong> previous chapter it was assumed that <strong>the</strong> lifting<br />
<strong>of</strong> low-speed fluid from <strong>the</strong> wall is mainly caused by <strong>the</strong> high-momentum <strong>flow</strong> <strong>structures</strong><br />
which move towards <strong>the</strong> wall. This interaction is shown exemplary in figure 7.19. Clearly<br />
visible is <strong>the</strong> strong wall-ward motion <strong>of</strong> a large-scale high-momentum <strong>flow</strong> structure in <strong>the</strong><br />
lower image and <strong>the</strong> generation <strong>of</strong> looped shaped <strong>structures</strong> similar to those shown in <strong>the</strong><br />
previous figure. <strong>The</strong> upper figure reveals similar <strong>structures</strong> but it should be noted that <strong>the</strong><br />
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FIGURE 7.19: Same as figure 7.18 but with strong sweeps (041~ž and 563~ž ).<br />
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