Redistribution of velocity and bed-shear stress in straight and curved open channels by means of a bubble screen: laboratory experiments

K. Blanckaert, F.A. Buschman, R. Schielen, J.H.A. Wijbenga

Research output: Contribution to journalArticleAcademicpeer-review

16 Citations (Scopus)

Abstract

Open-channel beds show variations in the transverse direction due to the interaction between downstream flow, cross-stream flow, and bed topography, which may reduce the navigable width or endanger the foundations of structures. The reported preliminary laboratory study shows that a bubble screen can generate cross-stream circulation that redistributes velocities and hence, would modify the topography. In straight flow, the bubble-generated cross-stream circulation cell covers a spanwise extent of about four times the water depth and has maximum transverse velocities of about 0.2 ms¿1. In sharply curved flow, it is slightly weaker and narrower with a spanwise extent of about three times the flow depth. It shifts the counter-rotating curvature-induced cross-stream circulation cell in the inwards direction. Maximum bubble-generated cross-stream circulation velocities are of a similar order of magnitude to typical curvature-induced cross-stream circulation velocities in natural open-channel bends. The bubble screen technique is adjustable, reversible, and ecologically favorable. Detailed data on the 3D flow field in open-channel bends is provided, which can be useful for validation of numerical models
Original languageEnglish
Pages (from-to)184-195
JournalJournal of Hydraulic Engineering
Volume134
Issue number2
DOIs
Publication statusPublished - 2008

Keywords

  • hydraulic engineering
  • channels
  • hydrodynamics
  • water flow
  • bending
  • redistribution
  • velocity
  • turbulence
  • laboratory tests
  • submerged vanes
  • secondary flows
  • alternate bars
  • topography
  • bends
  • rivers

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