Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension
Laboratory experiments examined the impact of model vegetation on wave-driven resuspension. Model canopies were constructed from cylinders with three diameters (d = 0.32, 0.64, and 1.26 cm) and 12 densities (cylinders/m2) up to a solid volume fraction (ϕ) of 10%. The sediment bed consisted of spheri...
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| Format: | Article |
| Language: | English |
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American Geophysical Union (AGU)
2020
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| Online Access: | https://hdl.handle.net/1721.1/125766 |
| _version_ | 1826192160595116032 |
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| author | Tang, Caihong Lei, Jiarui 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 Tang, Caihong Lei, Jiarui Nepf, Heidi |
| author_sort | Tang, Caihong |
| collection | MIT |
| description | Laboratory experiments examined the impact of model vegetation on wave-driven resuspension. Model canopies were constructed from cylinders with three diameters (d = 0.32, 0.64, and 1.26 cm) and 12 densities (cylinders/m2) up to a solid volume fraction (ϕ) of 10%. The sediment bed consisted of spherical grains with d50 = 85 μm. For each experiment, the wave velocity was gradually adjusted by increasing the amplitude of 2-s waves in a stepwise fashion. A Nortek Vectrino sampled the velocity at z = 1.3 cm above the bed. The critical wave orbital velocity for resuspension was inferred from records of suspended sediment concentration (measured with optical backscatter) as a function of wave velocity. The critical wave velocity decreased with increasing solid volume fraction. The reduction in critical wave velocity was linked to stem-generated turbulence, which, for the same wave velocity, increased with increasing solid volume fraction. The measured turbulence was consistent with a wave-modified version of a stem-turbulence model. The measurements suggested that a critical value of turbulent kinetic energy was needed to initiate resuspension, and this was used to define the critical wave velocity as a function of solid volume fraction. The model predicted the measured critical wave velocity for stem diameters d = 0.64 to 2 cm. Combining the critical wave velocity with an existing model for wave damping defined the meadow size for which wave damping would be sufficient to suppress wave-induced sediment suspension within the interior of the meadow. |
| first_indexed | 2024-09-23T09:06:49Z |
| format | Article |
| id | mit-1721.1/125766 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T09:06:49Z |
| publishDate | 2020 |
| publisher | American Geophysical Union (AGU) |
| record_format | dspace |
| spelling | mit-1721.1/1257662022-09-30T13:32:17Z Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension Tang, Caihong Lei, Jiarui Nepf, Heidi Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Laboratory experiments examined the impact of model vegetation on wave-driven resuspension. Model canopies were constructed from cylinders with three diameters (d = 0.32, 0.64, and 1.26 cm) and 12 densities (cylinders/m2) up to a solid volume fraction (ϕ) of 10%. The sediment bed consisted of spherical grains with d50 = 85 μm. For each experiment, the wave velocity was gradually adjusted by increasing the amplitude of 2-s waves in a stepwise fashion. A Nortek Vectrino sampled the velocity at z = 1.3 cm above the bed. The critical wave orbital velocity for resuspension was inferred from records of suspended sediment concentration (measured with optical backscatter) as a function of wave velocity. The critical wave velocity decreased with increasing solid volume fraction. The reduction in critical wave velocity was linked to stem-generated turbulence, which, for the same wave velocity, increased with increasing solid volume fraction. The measured turbulence was consistent with a wave-modified version of a stem-turbulence model. The measurements suggested that a critical value of turbulent kinetic energy was needed to initiate resuspension, and this was used to define the critical wave velocity as a function of solid volume fraction. The model predicted the measured critical wave velocity for stem diameters d = 0.64 to 2 cm. Combining the critical wave velocity with an existing model for wave damping defined the meadow size for which wave damping would be sufficient to suppress wave-induced sediment suspension within the interior of the meadow. National Science Foundation (Grant 1659923) 2020-06-11T17:51:51Z 2020-06-11T17:51:51Z 2019-07 2019-06 2020-05-29T17:23:01Z Article http://purl.org/eprint/type/JournalArticle 0043-1397 1944-7973 https://hdl.handle.net/1721.1/125766 Tang, Caihong et al. "Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension." Water Resources Research 55, 7 (July 2019): 5904-5917 © 2019 American Geophysical Union en http://dx.doi.org/10.1029/2018wr024335 Water Resources Research 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 American Geophysical Union (AGU) Other repository |
| spellingShingle | Tang, Caihong Lei, Jiarui Nepf, Heidi Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension |
| title | Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension |
| title_full | Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension |
| title_fullStr | Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension |
| title_full_unstemmed | Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension |
| title_short | Impact of Vegetation‐Generated Turbulence on the Critical, Near‐Bed, Wave‐Velocity for Sediment Resuspension |
| title_sort | impact of vegetation generated turbulence on the critical near bed wave velocity for sediment resuspension |
| url | https://hdl.handle.net/1721.1/125766 |
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