Journal ArticleDOI
The structure of the shear layer in flows over rigid and flexible canopies
Marco Ghisalberti,Heidi Nepf +1 more
TLDR
In this paper, the structure of coherent vortices and vertical transport in shallow vegetated shear flows were studied with rigid and flexible model vegetation to study coherent waving of flexible canopies.Abstract:
Flume experiments were conducted with rigid and flexible model vegetation to study the structure of coherent vortices (a manifestation of the Kelvin–Helmholtz instability) and vertical transport in shallow vegetated shear flows. The vortex street in a vegetated shear layer creates a pronounced oscillation in the velocity profile, with the velocity near the top of a model canopy varying by a factor of three during vortex passage. In turn, this velocity oscillation drives the coherent waving of flexible canopies. Relative to flows over rigid vegetation, the oscillation in canopy geometry has the effect of decreasing the amount of turbulent vertical momentum transport in the shear layer. Using a waving plant to determine phase in the vortex cycle, each vortex is shown to consist of a strong sweep at its front (during which the canopy is most deflected), followed by a weak ejection at its rear (when the canopy height is at a maximum). Whereas in unobstructed mixing layers the vortices span the entire layer, they encompass only 70% of the flexibly obstructed shear layer studied here.read more
Citations
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Journal ArticleDOI
Flow and Transport in Regions with Aquatic Vegetation
TL;DR: In this paper, the mean and turbulent flow and mass transport in the presence of aquatic vegetation is described. But the authors do not consider the effect of canopy-scale vortices on mass transport.
Flow and Transport in Regions with Aquatic Vegetation
TL;DR: In this paper, the mean and turbulent flow and mass transport in the presence of aquatic vegetation is described. But the authors do not consider the effect of canopy-scale vortices on mass transport.
Journal ArticleDOI
Flow and transport in channels with submerged vegetation
Heidi Nepf,Marco Ghisalberti +1 more
TL;DR: In this article, the authors reviewed recent work on flow and transport in channels with submerged vegetation, including discussions of turbulence structure, mean velocity profiles, and dispersion. And they showed that the dominant characteristic of the flow is the generation of a shear-layer at the top of the canopy.
Journal ArticleDOI
Hydrodynamics of aquatic ecosystems: An interface between ecology, biomechanics and environmental fluid mechanics
TL;DR: The Hydrodynamics of Aquatic Ecosystems (HOE) as discussed by the authors is an emerging research area at the interfaces between aquatic ecology, biomechanics and environmental fluid mechanics.
Journal ArticleDOI
Hurricane-induced failure of low salinity wetlands
Nick Howes,Duncan M. FitzGerald,Zoe J. Hughes,Ioannis Y. Georgiou,Mark Kulp,Michael D. Miner,Jane McKee Smith,John A. Barras +7 more
TL;DR: Geotechnical differences between the soil profiles of high and low salinity regimes, which are controlled by vegetation and result in differential erosion, suggest that the introduction of freshwater to marshes as part of restoration efforts may weaken existing wetlands rendering them vulnerable to hurricanes.
References
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Journal ArticleDOI
On density effects and large structure in turbulent mixing layers
Garry L. Brown,Anatol Roshko +1 more
TL;DR: In this article, Spark shadow pictures and measurements of density fluctuations suggest that turbulent mixing and entrainment is a process of entanglement on the scale of the large structures; some statistical properties of the latter are used to obtain an estimate of entrainedment rates, and large changes of the density ratio across the mixing layer were found to have a relatively small effect on the spreading angle.
Journal ArticleDOI
Turbulence in plant canopies
TL;DR: In this article, the mean velocity profile is inflected, second moments are strongly inhomogeneous with height, skewnesses are large, and second-moment budgets are far from local equilibrium.
Book ChapterDOI
Coherent eddies and turbulence in vegetation canopies: The mixing-layer analogy
TL;DR: In this paper, the authors argue that the active turbulence and coherent motions near the top of a vegetation canopy are patterned on a plane mixing layer, because of instabilities associated with the characteristic strong inflection in the mean velocity profile.
Journal ArticleDOI
The wall region in turbulent shear flow
TL;DR: In this article, the instantaneous product signal uv was classified according to the sign of its components u and v, and these classified portions were then averaged to obtain their contributions to the Reynolds stress.
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Mixing layers and coherent structures in vegetated aquatic flows
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