Rough Wall Boundary Layer on Plates in Open Channels
Publication: Journal of Hydraulic Engineering
Volume 128, Issue 10
Abstract
Experiments were performed to measure the characteristics of a turbulent boundary layer developing on a rough surface placed in an open channel flow at close proximity to the free surface. Streamwise velocity measurements were made with a one-component laser Doppler velocimeter system at the top of the spherical roughness elements. Measurements at three stations downstream of the plate leading edge show the growth of the boundary layer on the rough wall and its interaction with the exterior open-channel flow and the free surface. Resorting to the turbulence profile provides an alternative definition of the boundary layer thickness. The near-wall flow follows the well-known logarithmic law with a shift due to roughness. In the outer layer, there are two opposing effects: the free surface tends to decrease the wake component while the roughness tends to increase it. The streamwise turbulence intensity is affected by the shear and turbulence in the exterior flow, the effect of the free surface being greater than that of wall roughness.
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 128 • Issue 10 • October 2002
Pages: 947 - 951
Copyright
Copyright © 2002 American Society of Civil Engineers.
History
Received: Sep 26, 2001
Accepted: May 28, 2002
Published online: Sep 13, 2002
Published in print: Oct 2002
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