Seagrass deformation affects fluid instability and tracer exchange in canopy flow
Abstract Monami is the synchronous waving of a submerged seagrass bed in response to unidirectional fluid flow. Here we develop a multiphase model for the dynamical instabilities and flow-driven collective motions of buoyant, deformable seagrass. We show that the impedance to flow due to the seagras...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2023-03-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-023-30401-9 |
| _version_ | 1797864754810716160 |
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| author | Guilherme S. Vieira Michael R. Allshouse Amala Mahadevan |
| author_facet | Guilherme S. Vieira Michael R. Allshouse Amala Mahadevan |
| author_sort | Guilherme S. Vieira |
| collection | DOAJ |
| description | Abstract Monami is the synchronous waving of a submerged seagrass bed in response to unidirectional fluid flow. Here we develop a multiphase model for the dynamical instabilities and flow-driven collective motions of buoyant, deformable seagrass. We show that the impedance to flow due to the seagrass results in an unstable velocity shear layer at the canopy interface, leading to a periodic array of vortices that propagate downstream. Our simplified model, configured for unidirectional flow in a channel, provides a better understanding of the interaction between these vortices and the seagrass bed. Each passing vortex locally weakens the along-stream velocity at the canopy top, reducing the drag and allowing the deformed grass to straighten up just beneath it. This causes the grass to oscillate periodically even in the absence of water waves. Crucially, the maximal grass deflection is out of phase with the vortices. A phase diagram for the onset of instability shows its dependence on the fluid Reynolds number and an effective buoyancy parameter. Less buoyant grass is more easily deformed by the flow and forms a weaker shear layer, with smaller vortices and less material exchange across the canopy top. While higher Reynolds number leads to stronger vortices and larger waving amplitudes of the seagrass, waving amplitude is maximized at intermediate grass buoyancy. All together, our theory and computations develop an updated schematic of the instability mechanism consistent with experimental observations. |
| first_indexed | 2024-04-09T22:57:17Z |
| format | Article |
| id | doaj.art-685ff0893de84b2a8597e43b5c11c979 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-09T22:57:17Z |
| publishDate | 2023-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-685ff0893de84b2a8597e43b5c11c9792023-03-22T11:11:17ZengNature PortfolioScientific Reports2045-23222023-03-0113111310.1038/s41598-023-30401-9Seagrass deformation affects fluid instability and tracer exchange in canopy flowGuilherme S. Vieira0Michael R. Allshouse1Amala Mahadevan2Department of Mechanical and Industrial Engineering, Northeastern UniversityDepartment of Mechanical and Industrial Engineering, Northeastern UniversityWoods Hole Oceanographic InstitutionAbstract Monami is the synchronous waving of a submerged seagrass bed in response to unidirectional fluid flow. Here we develop a multiphase model for the dynamical instabilities and flow-driven collective motions of buoyant, deformable seagrass. We show that the impedance to flow due to the seagrass results in an unstable velocity shear layer at the canopy interface, leading to a periodic array of vortices that propagate downstream. Our simplified model, configured for unidirectional flow in a channel, provides a better understanding of the interaction between these vortices and the seagrass bed. Each passing vortex locally weakens the along-stream velocity at the canopy top, reducing the drag and allowing the deformed grass to straighten up just beneath it. This causes the grass to oscillate periodically even in the absence of water waves. Crucially, the maximal grass deflection is out of phase with the vortices. A phase diagram for the onset of instability shows its dependence on the fluid Reynolds number and an effective buoyancy parameter. Less buoyant grass is more easily deformed by the flow and forms a weaker shear layer, with smaller vortices and less material exchange across the canopy top. While higher Reynolds number leads to stronger vortices and larger waving amplitudes of the seagrass, waving amplitude is maximized at intermediate grass buoyancy. All together, our theory and computations develop an updated schematic of the instability mechanism consistent with experimental observations.https://doi.org/10.1038/s41598-023-30401-9 |
| spellingShingle | Guilherme S. Vieira Michael R. Allshouse Amala Mahadevan Seagrass deformation affects fluid instability and tracer exchange in canopy flow Scientific Reports |
| title | Seagrass deformation affects fluid instability and tracer exchange in canopy flow |
| title_full | Seagrass deformation affects fluid instability and tracer exchange in canopy flow |
| title_fullStr | Seagrass deformation affects fluid instability and tracer exchange in canopy flow |
| title_full_unstemmed | Seagrass deformation affects fluid instability and tracer exchange in canopy flow |
| title_short | Seagrass deformation affects fluid instability and tracer exchange in canopy flow |
| title_sort | seagrass deformation affects fluid instability and tracer exchange in canopy flow |
| url | https://doi.org/10.1038/s41598-023-30401-9 |
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