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Flow structure in canopy models dominated by progressive waves

Laboratory experiments were carried out to study the flow structure both inside and above different canopy models which were dominated by progressive waves. A set of experimental conditions were considered in a laboratory flume: three vegetation models (submerged rigid, submerged flexible and emergent rigid), three plant densities (128, 640 and 1280stemsm-2) and three wave frequencies (f=0.8, 1 and 1.4Hz). The progressive waves followed the second-order Stokes theory in the intermediate depth range. The observations revealed that submerged and emergent rigid vegetation models modified the wave-induced velocities i.e., both mean current and wave velocity. The submerged rigid vegetation model for plant densities higher than 640plantsm-2 and wave frequency higher than 1Hz acted akin to a false floor, confining the mean current to above the plant bed. A penetration depth around 2cm below the top of submerged rigid vegetation was found. For the other runs, the vertical profile of mean current did not present changes with respect to runs without plants. The emergent rigid vegetation model reversed the direction of the induced mean current, with the highest velocity corresponding to the highest plant density. In contrast, the submerged flexible vegetation model had a weak effect on the mean current, with the vertical velocity profile similar to that found in experiments without vegetation. The wave velocities inside the vegetation for the densest submerged rigid vegetation were found to be reduced by 20%, when compared to the wave velocities without vegetation, while in emergent rigid vegetation this reduction was of 45%

Dolors Pujol was supported by the research fellowship BR08/11 of the University of Girona. We are also grateful to the Spanish Government鈥檚 support through the Ministerio de Ciencia e Innovaci贸n with Grant CGL 2010-17289 and to the support from the Fundaci贸n Biodiversidad (AIN2011B)

漏 Journal of Hydrology, 2013, vol. 486, p. 281-292

Elsevier

Author: Pujol, Dolors
Serra Putellas, Teresa
Colomer, Jordi
Casamitjana, Xavier
Date: 2013 April 12
Abstract: Laboratory experiments were carried out to study the flow structure both inside and above different canopy models which were dominated by progressive waves. A set of experimental conditions were considered in a laboratory flume: three vegetation models (submerged rigid, submerged flexible and emergent rigid), three plant densities (128, 640 and 1280stemsm-2) and three wave frequencies (f=0.8, 1 and 1.4Hz). The progressive waves followed the second-order Stokes theory in the intermediate depth range. The observations revealed that submerged and emergent rigid vegetation models modified the wave-induced velocities i.e., both mean current and wave velocity. The submerged rigid vegetation model for plant densities higher than 640plantsm-2 and wave frequency higher than 1Hz acted akin to a false floor, confining the mean current to above the plant bed. A penetration depth around 2cm below the top of submerged rigid vegetation was found. For the other runs, the vertical profile of mean current did not present changes with respect to runs without plants. The emergent rigid vegetation model reversed the direction of the induced mean current, with the highest velocity corresponding to the highest plant density. In contrast, the submerged flexible vegetation model had a weak effect on the mean current, with the vertical velocity profile similar to that found in experiments without vegetation. The wave velocities inside the vegetation for the densest submerged rigid vegetation were found to be reduced by 20%, when compared to the wave velocities without vegetation, while in emergent rigid vegetation this reduction was of 45%
Dolors Pujol was supported by the research fellowship BR08/11 of the University of Girona. We are also grateful to the Spanish Government鈥檚 support through the Ministerio de Ciencia e Innovaci贸n with Grant CGL 2010-17289 and to the support from the Fundaci贸n Biodiversidad (AIN2011B)
Format: application/pdf
ISSN: 0022-1694
Document access: http://hdl.handle.net/10256/13475
Language: eng
Publisher: Elsevier
Collection: MICINN/PN 2011-2013/CGL2010-17289
Reproducci贸 digital del document publicat a: http://dx.doi.org/10.1016/j.jhydrol.2013.01.024
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Is part of: 漏 Journal of Hydrology, 2013, vol. 486, p. 281-292
Rights: Tots els drets reservats
Subject: Ones
Waves
Turbul猫ncia
Turbulence
Din脿mica de fluids
Fluid dynamics
Title: Flow structure in canopy models dominated by progressive waves
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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