Effects of Groyne Layout on the Flow in Groyne Fields: Laboratory Experiments

This research is aimed at finding efficient alternative designs, in the physical, economical, and ecological sense, for the standard groins as they are found in the large rivers of Europe. In order to test the effects of various groin shapes on the flow in a groin field, experiments were performed in a physical model of a schematized river reach, geometrically scaled 1:40. Four different types of schematized groins were tested, all arranged in an array of five identical groin fields, i.e., standard reference groins, groins with a head having a gentle slope and extending into the main channel, permeable groins consisting of pile rows, and hybrid groins consisting of a lowered impermeable groin with a pile row on top. Flow velocities were measured using particle tracking velocimetry. The design of the experiment was such that the cross-sectional area blocked by the groin was the same in all cases. Depending on the groin head shape and the extent of submergence variations in the intensity of vortex shedding and recirculation in the groin field were observed. The experimental data are used to understand the physical processes like vortex formation and detachment near the groin head. It is demonstrated that the turbulence properties near and downstream of the groin can be manipulated by changing the permeability and slope of the groin head. It is also observed that for submerged conditions the flow becomes complex and locally dominated by three-dimensional effects, which will make it difficult to predict by applying depth average numerical models or by three-dimensional models with a coarse resolution in the vertical direction.

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  • English

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  • Accession Number: 01003971
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 13 2005 6:16AM