Universal velocity defect law

Universal Velocity-Defect Law. Figure 5.7 shows the velocity profile computed from Eq. 5.65 together with Nikuradse s [43] measurement data. It can be observed that the velocity profile becomes flatter over most of the duct section, and the exponent 1 In of the power law of the velocity distribution, Eq. 5.65, decreases as Re increases. This observation led to the derivation of another form for velocity distribution, the universal velocity-defect law. The for-... 

Von Karman [46] derived the following form for the universal velocity-defect law ... 

The Prandtl-Karman-Nikuradse (PKN) correlation is based on the universal velocity-defect law with the coefficients slightly modified to fit the highly accurate experimental data reported by Nikuradse [43], which is known to be the most accurate. This correlation is also referred to as the universal law of friction. However, since the PKN formula gives/values... 

FIGURE 5.8 Universal velocity-defect law distribution for fully developed turbulent flow in a smooth circular duct [45]. 

Integrating this equation between y and 5 3uelds the velocity-defect law for the outer layer. This, of course, requires that the non-universal non-dimensional function, [Pg.128]

The velocity gradient is expressed in the form of the universal defect law as... 

The velocity distribution near the center of the flume followed Von Karman universal defect law. 

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