Vortex Structure and Sediment Deposition in the Wake behind a Finite Patch of Model Submerged Vegetation

Liu, Chao; Hu, Zhenghong; Lei, Jiarui; Nepf, Heidi

doi:10.1061/(asce)hy.1943-7900.0001408

Cited by 75 publications

(89 citation statements)

References 39 publications

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“…This result indicated that energy dispersion was inhibited because our observations showed that some of the flow disturbances were directed over the patch and did not accelerate at the edges. Similar behaviour was observed in the study of Liu, Hu, Lei, and Nepf () with patch heights of Z/H = 0.21 and 0.36.…”

Section: Discussionsupporting

confidence: 87%

Flow field downstream of individual aquatic plants—Experiments in a natural river with Potamogeton crispus L. and Myriophyllum spicatum L.

Przyborowski

Łoboda

Bialik

et al. 2019

Hydrological Processes

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Flow disturbances generated by individual patches of submerged, flexible aquatic vegetation were investigated for two naturally growing macrophyte species, Potamogeton crispus L. and Myriophyllum spicatum L., in a sandy lowland river. Through acoustic Doppler velocimetry, 24 vertical profiles of the 3D velocity field were recorded downstream of each of the patches. The morphological features and biomechanical properties of the plants were also evaluated. The experiments showed the relationship between biomechanical characteristics and turbulence statistics. M. spicatum, which was stiffer and therefore less prone to dynamic reconfiguration, showed a greater effect on velocity damping, causing an increase in Reynold stresses, turbulence intensities, and turbulent kinetic energy downstream of the patch. These effects were present in regions both above and below plant height. In contrast for P. crispus, these effects were present only below plant height. The stiffer plant produced a mixing layer in its wake similar to that of dense plant canopies. The patch of less stiff and more streamlined P. crispus with longer leaves presented a much weaker effect on the flow. In contrast to previous studies conducted with rigid plant surrogates, we concluded that reconfiguration of the living flexible plants allows the plants to minimize drag forces, and therefore, their influence on the flow field was weaker than the effects reported for rigid surrogates.

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Section: Discussionsupporting

confidence: 87%

Flow field downstream of individual aquatic plants—Experiments in a natural river with Potamogeton crispus L. and Myriophyllum spicatum L.

Przyborowski

Łoboda

Bialik

et al. 2019

Hydrological Processes

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“…The field data and CFD results on shear layer growth demonstrated that for pioneer saltmarsh vegetation ( Suaeda maritima ) patches, considering the ensemble‐averaged patch geometry, patch height controls wake length rather than patch width. This geometric control is similar to what Liu et al () discovered for submerged rigid vegetation patches. There are, however, key differences with their study.…”

Section: Discussionsupporting

confidence: 87%

“…For the horizontal shear layers, the maximum distance each shear layer can grow laterally before interfering is δ MAX ( w ) = w /2. The controlling factor for wake length will therefore depend on the ratio of w / h (Hu et al, ; Liu et al, ). If the vertical and horizontal shear layer characteristics (

\overset{U}{true} / S_{δ} normalΔ U

) are identical between the horizontal and vertical shear layers, then it follows that the smallest value of δ MAX will dictate the wake length.…”

Section: Resultsmentioning

confidence: 99%

“…There are, however, key differences with their study. First, their experiments were conducted with a high patch flow blockage, decreasing bleed flow and wake length (Chen et al, ; Liu et al, ). Second, here we consider flexible vegetation, and therefore as the plant reconfigures, h d and x d become significant.…”

Section: Discussionmentioning

confidence: 99%

“…In these cases, for given patch porosity and flow conditions, patch width determines wake length (Zong & Nepf, ). However, for submerged vegetation, the vertical shear layer formed at the top of the patch (Figure b) may be of equal or greater importance, depending on patch geometry (Hu et al, ; Liu et al, ). If wake length is controlled by the vertical shear layer instead of the horizontal shear layer, then shoot height, rather than patch width, will determine the wake length.…”

Section: Introductionmentioning

confidence: 99%

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Flexural Rigidity and Shoot Reconfiguration Determine Wake Length Behind Saltmarsh Vegetation Patches

et al. 2019

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Vegetation patches play an important role in controlling sediment deposition in shallow aquatic environments such as coastal saltmarshes and fluvial systems. However, predicting deposition around vegetation patches is difficult due to the complexity of patch morphology and their dynamic interaction with the flow. Here we incorporate a biomechanical model, parameterized using field data, within a 3‐D computational fluid dynamics model which allows prediction of individual shoot reconfiguration within patches due to flow forcing. The model predicts velocity attenuation and bed shear stresses within the wake of the patch which agree spatially with accretion patterns measured in the field using terrestrial lidar. The model is applied to sparse patches of Suaeda maritima, located in saltmarshes of coastal habitats, to explore the role of (I) shoot distribution, (II) patch geometry, (III) shoot flexural rigidity, and (IV) bulk flow velocity in determining the length of the predicted wake region. We demonstrate that for Suaeda maritima, with intermediate rigidity, the vertical shear layer over the vegetation controls the length of the predicted wake region. Consequently, reconfiguration due to flexural rigidity strongly impacts on wake length, confounding the relationship between patch height and wake length. A simplified model for predicting wake length based on shoot reconfiguration is applied to the simulation data and shows good agreement. The results demonstrate that the observed wake characteristics can be well explained by intraspecific variability in flexural rigidity, thus demonstrating the importance of biomechanical traits in determining flow‐vegetation‐sediment interactions.

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Organizational Principles of Hyporheic Exchange Flow and Biogeochemical Cycling in River Networks across Scales

Krause,

Abbott,

Baranov

et al. 2024

Ecohydrological Interfaces

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Vortex Structure and Sediment Deposition in the Wake behind a Finite Patch of Model Submerged Vegetation

Cited by 75 publications

References 39 publications

Flow field downstream of individual aquatic plants—Experiments in a natural river with Potamogeton crispus L. and Myriophyllum spicatum L.

Flow field downstream of individual aquatic plants—Experiments in a natural river with Potamogeton crispus L. and Myriophyllum spicatum L.

Flexural Rigidity and Shoot Reconfiguration Determine Wake Length Behind Saltmarsh Vegetation Patches

Organizational Principles of Hyporheic Exchange Flow and Biogeochemical Cycling in River Networks across Scales

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