Author(s): A. H. Cardoso; W. H. Graf; G. Gust
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Abstract: Laboratory experiments on the structure of fully developed smooth and steady open channel flows gradually subjected to spatial acceleration (Fig. 1) are reported. Mean velocity (Figs. 3 and 5) and turbulence intensity profiles (Fig. 6) as well as friction velocity (Fig. 4) were measured. It was found that: -1) self-similarity is not preserved over the entire depth of the accel-erated flow; -2) a very thin universal wall layer is likely to prevail; -3) the turbulence intensity distribution of uniform open channel flows does not hold for the accelerated flow; -4) the Clauser's method for the calculation of the friction velocity leads to erroneous results when applied to the velocity measurements obtained outside of the mentioned thin wall layer.
Year: 1989