The significance of coherent flow structures for the turbulent mixing ...

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7.2 Statistical properties of the log-law region
R (y
+
=30)
vw
R (y
+
=30)
wv
y
+
∆ y
+
y
+
∆ y
+
y
+
∆ y
+
R (y
+
=50)
vw
R (y
+
=50)
wv
R (y
+
=100) R (y
+
=100)
vw
wv
∆ z +
∆ z
+
FIGURE 7.9: ˜ ÔËÙÇÄ © » Æ © » È_É © » ÆËÉÌ » Í and ˜ Ù¥ÔwÄ © » Æ © » È_É © » ÆËÉÌ » Í correlation measured at © » š
Χž ÆËÏ ž ÆÐ žž .
distance with respect to the location of the fixed point, while in the case where ä the component
was fixed the maximum occurs closer to the wall. The same behaviour can be observed when
the cross-correlation between the wall-normal and span-wise component of the velocity is
considered. The left column in figure 7.9 displays ª^ÔËÙ the correlation function measured at
was shifted in
¥Ö ° &Ö (top to bottom). Here the ã component was fixed while å
¹&»\¬æÂ
the two homogeneous directions and the right column reveals the opposite case where å the
component was fixed ã while was shifted. It can be seen that the structures presented in the left
column are larger for all wall locations. In addition, a significant change in the organisation
of the correlation can be observed when the location of the fixed point is altered. In case
of the correlation presented in the right column the structural features remain constant with
increasing wall distance and only the size varies. The value of the maximum is comparable for
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