Mean flow and turbulence fields over two-dimensional bed forms

Water Resources Research
By: , and 

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Abstract

Detailed laser-Doppler velocity and Reynolds stress measurements over fixed two-dimensional bed forms are used to investigate the coupling between the mean flow and turbulence and to examine effects that play a role in producing the bed form instability and finite amplitude stability. The coupling between the mean flow and the turbulence is explored in both a spatially averaged sense, by determining the structure of spatially averaged velocity and Reynolds stress profiles, and a local sense, through computation of eddy viscosities and length scales. The measurements show that there is significant interaction between the internal boundary layer and the overlying wake turbulence produced by separation at the bed form crest. The interaction produces relatively low correlation coefficients in the internal boundary layer, which suggests that using local bottom stress to predict bed load flux may not only be erroneous, it may also disregard the essence of the bed form instability mechanism. The measurements also indicate that topographically induced acceleration over the bed form stoss slope has a more significant effect in damping the turbulence over bed forms than was previously supposed, which is hypothesized to play a role in the stabilization of fully developed bed forms.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Mean flow and turbulence fields over two-dimensional bed forms
Series title Water Resources Research
DOI 10.1029/93WR01932
Volume 29
Issue 12
Year Published 1993
Language English
Publisher American Geophysical Union
Description 9 p.
First page 3935
Last page 3953