Mean Flow and Turbulence in Open-Channel Bend
Publication: Journal of Hydraulic Engineering
Volume 127, Issue 10
Abstract
Flow over a developed bottom topography in a bend has been investigated experimentally. The measuring section is in the outer-bank half of the cross section at 60° into the bend. Spatial distributions of the mean velocities, turbulent stresses, and mean-flow and turbulent kinetic energy are presented. The cross-sectional motion contains two cells of circulation: besides the classical helical motion (center-region cell), a weaker counterrotating cell (outer-bank cell) is observed in the corner formed by the outer bank and the water surface. The downstream velocity in the outer half-section is higher than the one in straight uniform flow; the core of maximum velocities is found close to the separation between both circulation cells, well below the water surface. The turbulence structure in a bend is different from that in a straight flow, most notably in a reduction of the turbulent activity toward the outer bank. Both the outer-bank cell and reduced turbulent activity have a protective effect on the outer bank and the adjacent bottom and thus influence the stability of the flow perimeter and the bend morphology.
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Published In
Journal of Hydraulic Engineering
Volume 127 • Issue 10 • October 2001
Pages: 835 - 847
History
Received: Apr 4, 2000
Published online: Oct 1, 2001
Published in print: Oct 2001
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