Langmuir turbulence in suspended kelp farms

Fuente: arXiv
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Autori principali: Bo, Tong, McWilliams, James C., Yan, Chao, Chamecki, Marcelo
Natura: Preprint
Pubblicazione: 2024
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author Bo, Tong
McWilliams, James C.
Yan, Chao
Chamecki, Marcelo
author_facet Bo, Tong
McWilliams, James C.
Yan, Chao
Chamecki, Marcelo
contents This study investigates the influence of suspended kelp farms on ocean mixed layer hydrodynamics in the presence of currents and waves. We use the large eddy simulation method, where the wave effect is incorporated by solving the wave-averaged equations. Distinct Langmuir circulation patterns are generated within various suspended farm configurations, including horizontally uniform kelp blocks and spaced kelp rows. Intensified turbulence arises from the farm-generated Langmuir circulation, as opposed to the standard Langmuir turbulence observed without a farm. The creation of Langmuir circulation within the farm is attributed to two primary factors depending on farm configuration: (1) enhanced vertical shear due to kelp frond area density variability, and (2) enhanced lateral shear due to canopy discontinuity at lateral edges of spaced rows. Both enhanced vertical and lateral shear of streamwise velocity, representing the lateral and vertical vorticity components respectively, can be tilted into downstream vorticity to create Langmuir circulation. This vorticity tilting is driven by the Craik- Leibovich vortex force associated with the Stokes drift of surface gravity waves. In addition to the farm-generated Langmuir turbulence, canopy shear layer turbulence is created at the farm bottom edge due to drag discontinuity. The intensity of different types of turbulence depends on both kelp frond area density and the geometric configuration of the farm. The farm-generated turbulence has substantial consequences for nutrient supply and kelp growth. These findings also underscore the significance of the presence of obstacle structures in modifying ocean mixed layer characteristics.
format Preprint
id arxiv_https___arxiv_org_abs_2403_04947
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Langmuir turbulence in suspended kelp farms
Bo, Tong
McWilliams, James C.
Yan, Chao
Chamecki, Marcelo
Fluid Dynamics
Atmospheric and Oceanic Physics
This study investigates the influence of suspended kelp farms on ocean mixed layer hydrodynamics in the presence of currents and waves. We use the large eddy simulation method, where the wave effect is incorporated by solving the wave-averaged equations. Distinct Langmuir circulation patterns are generated within various suspended farm configurations, including horizontally uniform kelp blocks and spaced kelp rows. Intensified turbulence arises from the farm-generated Langmuir circulation, as opposed to the standard Langmuir turbulence observed without a farm. The creation of Langmuir circulation within the farm is attributed to two primary factors depending on farm configuration: (1) enhanced vertical shear due to kelp frond area density variability, and (2) enhanced lateral shear due to canopy discontinuity at lateral edges of spaced rows. Both enhanced vertical and lateral shear of streamwise velocity, representing the lateral and vertical vorticity components respectively, can be tilted into downstream vorticity to create Langmuir circulation. This vorticity tilting is driven by the Craik- Leibovich vortex force associated with the Stokes drift of surface gravity waves. In addition to the farm-generated Langmuir turbulence, canopy shear layer turbulence is created at the farm bottom edge due to drag discontinuity. The intensity of different types of turbulence depends on both kelp frond area density and the geometric configuration of the farm. The farm-generated turbulence has substantial consequences for nutrient supply and kelp growth. These findings also underscore the significance of the presence of obstacle structures in modifying ocean mixed layer characteristics.
title Langmuir turbulence in suspended kelp farms
topic Fluid Dynamics
Atmospheric and Oceanic Physics
url https://arxiv.org/abs/2403.04947