Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition
The transport of fine sediment and organic matter plays an important role in the nutrient dynamics of shallow aquatic systems, and the fate of these particles is closely linked to vegetation. We describe the mean and turbulent flow near circular patches of synthetic vegetation and examine how the sp...
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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John Wiley & Sons, Inc/American Geophysical Union
2014
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| Online Access: | http://hdl.handle.net/1721.1/89461 https://orcid.org/0000-0001-8326-9037 |
| _version_ | 1811072007497842688 |
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| author | Ortiz, Alejandra Campbell Ashton, Andrew Nepf, Heidi |
| author2 | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Ortiz, Alejandra Campbell Ashton, Andrew Nepf, Heidi |
| author_sort | Ortiz, Alejandra Campbell |
| collection | MIT |
| description | The transport of fine sediment and organic matter plays an important role in the nutrient dynamics of shallow aquatic systems, and the fate of these particles is closely linked to vegetation. We describe the mean and turbulent flow near circular patches of synthetic vegetation and examine how the spatial distribution of flow is connected to the spatial distribution of suspended sediment deposition. Patches of rigid, emergent, and flexible, submerged vegetation were considered, with two different stem densities. For the rigid emergent vegetation, flow adjustment was primarily two-dimensional, with flow deflected in the horizontal plane. Horizontal shear layers produced a von Kármán vortex street. Flow through the patch shifted the vortex street downstream, resulting in a region directly downstream of the patch in which both the mean and turbulent velocities were diminished. Net deposition was enhanced within this region. In contrast, for the flexible, submerged vegetation, flow adjustment was three-dimensional, with shear layers formed in the vertical and horizontal planes. Because of strong vertical circulation, turbulent kinetic energy was elevated directly downstream of the patch. Consistent with this, deposition was not enhanced at any point in the wake. This comparison suggests that morphological feedbacks differ between submerged and emergent vegetation. Further, enhanced deposition occurred only in regions where both turbulent and mean velocities were reduced, relative to the open channel. Reduced deposition (indicating enhanced resuspension) occurred in regions of high turbulence kinetic energy, regardless of local mean velocity. These observations highlight the importance of turbulence in controlling deposition. |
| first_indexed | 2024-09-23T08:59:25Z |
| format | Article |
| id | mit-1721.1/89461 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:59:25Z |
| publishDate | 2014 |
| publisher | John Wiley & Sons, Inc/American Geophysical Union |
| record_format | dspace |
| spelling | mit-1721.1/894612022-09-26T09:38:47Z Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition Ortiz, Alejandra Campbell Ashton, Andrew Nepf, Heidi Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Ortiz, Alejandra Campbell Nepf, Heidi The transport of fine sediment and organic matter plays an important role in the nutrient dynamics of shallow aquatic systems, and the fate of these particles is closely linked to vegetation. We describe the mean and turbulent flow near circular patches of synthetic vegetation and examine how the spatial distribution of flow is connected to the spatial distribution of suspended sediment deposition. Patches of rigid, emergent, and flexible, submerged vegetation were considered, with two different stem densities. For the rigid emergent vegetation, flow adjustment was primarily two-dimensional, with flow deflected in the horizontal plane. Horizontal shear layers produced a von Kármán vortex street. Flow through the patch shifted the vortex street downstream, resulting in a region directly downstream of the patch in which both the mean and turbulent velocities were diminished. Net deposition was enhanced within this region. In contrast, for the flexible, submerged vegetation, flow adjustment was three-dimensional, with shear layers formed in the vertical and horizontal planes. Because of strong vertical circulation, turbulent kinetic energy was elevated directly downstream of the patch. Consistent with this, deposition was not enhanced at any point in the wake. This comparison suggests that morphological feedbacks differ between submerged and emergent vegetation. Further, enhanced deposition occurred only in regions where both turbulent and mean velocities were reduced, relative to the open channel. Reduced deposition (indicating enhanced resuspension) occurred in regions of high turbulence kinetic energy, regardless of local mean velocity. These observations highlight the importance of turbulence in controlling deposition. National Science Foundation (U.S.) (grant EAR 0738352) National Science Foundation (U.S.) (grant OCE0751358) 2014-09-12T15:25:23Z 2014-09-12T15:25:23Z 2013-12 2013-11 Article http://purl.org/eprint/type/JournalArticle 21699003 http://hdl.handle.net/1721.1/89461 Ortiz, Alejandra C., Andrew Ashton, and Heidi Nepf. “Mean and Turbulent Velocity Fields Near Rigid and Flexible Plants and the Implications for Deposition.” Journal of Geophysical Research: Earth Surface 118, no. 4 (December 2013): 2585–2599. https://orcid.org/0000-0001-8326-9037 en_US http://dx.doi.org/10.1002/2013jf002858 Journal of Geophysical Research: Earth Surface Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf John Wiley & Sons, Inc/American Geophysical Union MIT web domain |
| spellingShingle | Ortiz, Alejandra Campbell Ashton, Andrew Nepf, Heidi Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| title | Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| title_full | Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| title_fullStr | Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| title_full_unstemmed | Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| title_short | Mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| title_sort | mean and turbulent velocity fields near rigid and flexible plants and the implications for deposition |
| url | http://hdl.handle.net/1721.1/89461 https://orcid.org/0000-0001-8326-9037 |
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