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You are here : eLibrary : IAHR World Congress Proceedings : 34th Congress - Brisbane (2011) : THEME 5: Environmental Hydraulics and Hydrology : Invalidity of classical log-law and its mechanism
Invalidity of classical log-law and its mechanism
Author : Shu-Qing Yang
This paper investigates the invalidity of classical log-law and its underlying mechanism in pipe and channel flows. It is widely reported that the log-law is only valid for velocity profile in the near wall region, in outer flow region, the measured velocity is systematically higher (wake-law) or lower than the log-law’s prediction, but these deviations have not been well explained. By dividing the wall-normal velocity fluctuation into upward and downward conditions, the conditionally-averaged momentum equations are derived. The theoretical results show that the momentum flux caused by the conditionally upward/downward velocity leads to the invalidity. Based on this discovery, a new equation is proposed to express the velocity, and good agreement is achieved between the measured and predicted velocities
File Size : 381,541 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 34th Congress - Brisbane (2011)
Article : THEME 5: Environmental Hydraulics and Hydrology
Date Published : 01/07/2011
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