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On the influence of bed permeability on flow in the leeside of coarse-grained bedforms
Blois, G.; Best, J.L.; Smith, G.S.; Hardy, R.J. (2013). On the influence of bed permeability on flow in the leeside of coarse-grained bedforms, in: Van Lancker, V. et al. (Ed.) MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013. VLIZ Special Publication, 65: pp. 39-44
In: Van Lancker, V.; Garlan, T. (Ed.) (2013). MARID 2013: Fourth International Conference on Marine and River Dune Dynamics. Bruges, Belgium, 15-17 April 2013. VLIZ Special Publication, 65. Royal Belgian Institute of Natural Sciences/SHOM/Flanders Marine Institute (VLIZ): Oostende. ISBN 978-2-11-128352-7. 338 pp., more
In: VLIZ Special Publication. Vlaams Instituut voor de Zee (VLIZ): Oostende. ISSN 1377-0950, more

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Keyword
    Fresh water

Authors  Top 
  • Blois, G.
  • Best, J.L.
  • Smith, G.S.
  • Hardy, R.J.

Abstract
    This paper details the dynamics of coherent flow structures generated in shallow flows around impermeable and permeable 2-dimensional bedforms overlaying a highly-permeable idealised bed. Particle imaging velocimetry (PIV) measurements were idealised 2-dimensional dunes overlaying a packed bed of uniform size spheres. Experiments were conducted in free surface flow conditions (Froude number = 0.1; Reynolds number = 25,000) for dune was measured using a standard PIV technique while a novel endoscopic PIV (EPIV) system allowed collection of flow data within the pore spaces beneath the dune. These results show that the permeability of the bed has a critical impact on flow around the bedform, inducing a significant interaction between the free-flow and subsurface flow. The interaction between the free-flow and hyporheic flow is significant; in the leeside, recirculation in the separation zone is replaced by a mechanism of asymmetric alternate vortex shedding. The paper will discuss the implications of these results for the morphodynamics of coarse-sediment bedforms.

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