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You are here : eLibrary : IAHR World Congress Proceedings : 33rd Congress - Vancouver (2009) : Topic A: Advances in the Fundamentals of Water Science and Engineering : On the nature of coherent turbulent structures in channel bends: burst-sweep orientations in three-d...
On the nature of coherent turbulent structures in channel bends: burst-sweep orientations in three-dimensional flow fields
Author : M. Tilston, C. Rennie, R.W.C. Arnott and G. Post
It is widely accepted that natural flows are characterized by coherent turbulent structures, known
as bursts and sweeps, which transfer fluid momentum across local velocity gradients. While
these have been the subject of extensive laboratory and field investigations, no studies have
attempted to address their characteristics in channel bends. In part, this is related to the existing
analytical frameworks, which are inherently two dimensional. The objectives of this study are to
a) develop a fully three-dimensional scheme for analysing coherent turbulent structures; b)
investigate the orientation of bursts and sweeps in an experimental channel bend. This involves
solving the Reynolds tensor and performing octant analysis in lieu of conventional twodimensional
approaches. Results indicate that bursts and sweeps lack a preferred orientation
upstream and downstream of the bend. However, flow in the channel bend strongly displays
inner-bank oriented bursts and outer-bank oriented sweeps. These findings suggest that burstsweep
orientations are controlled by vertical gradient of the cross-stream velocity component and
turbulence generated fluctuations in the cross-stream force balance.
File Size : 1,783,727 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 33rd Congress - Vancouver (2009)
Article : Topic A: Advances in the Fundamentals of Water Science and Engineering
Date Published : 09/08/2009
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