Statistical Uncertainty and the Estimation of Log Law Parameters
Publication: Journal of Hydraulic Engineering
Volume 134, Issue 9
Abstract
It is experimentally demonstrated that fitting the log law to the mean velocity profile in turbulent open-channel flow to determine the friction velocity, roughness length, and zero-plane displacement, can lead to relatively high standard errors in these parameters. It is also demonstrated that this approach, where the log law alone is used to estimate these parameters, may yield values of these parameters that are significantly different from those obtained when the friction velocity is determined independently of the log law. Although the statistical estimation of the three log law parameters from mean velocity data alone is frequently necessary, this procedure can lead to inaccurate and imprecise estimates of these quantities.
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Acknowledgments
The writers gratefully acknowledge the support of the National Science Foundation, NSF Grant No. NSFEAR-0439663.
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 134 • Issue 9 • September 2008
Pages: 1353 - 1356
Copyright
© 2008 ASCE.
History
Received: Jul 13, 2004
Accepted: Jul 23, 2007
Published online: Sep 1, 2008
Published in print: Sep 2008
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