Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium
Erosion and flooding are the main threats for most coastal regions. Nature-based solutions, such as coastal vegetation (CV) fields, have received significant attention in recent years because they effectively dissipate wave energy while maintaining biodiversity. In this study, a porous medium model...
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| Language: | English |
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MDPI AG
2023-02-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/11/3/519 |
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| author | Iason A. Chalmoukis Georgios A. Leftheriotis Athanassios A. Dimas |
| author_facet | Iason A. Chalmoukis Georgios A. Leftheriotis Athanassios A. Dimas |
| author_sort | Iason A. Chalmoukis |
| collection | DOAJ |
| description | Erosion and flooding are the main threats for most coastal regions. Nature-based solutions, such as coastal vegetation (CV) fields, have received significant attention in recent years because they effectively dissipate wave energy while maintaining biodiversity. In this study, a porous medium model was implemented in an in-house software to simulate the three-dimensional, two-phase (water/air) flow induced by wave propagation past CV fields. First, the model was validated against experimental measurements of wave propagation past a CV field on a horizontal bed. Then, the model was used to assess the influence on wave behaviour of the equivalent porosity, <i>n<sub>eq</sub></i>, and the cross-shore length, <i>L<sub>CV</sub></i>, of a CV field with a constant plant height on a beach with a constant bed slope. Results were obtained for the non-vegetated case (<i>n<sub>eq</sub></i> = 1) and five vegetated cases with different <i>n<sub>eq</sub></i> and <i>L<sub>CV</sub></i> values. It was found that decreasing <i>n<sub>eq</sub></i> moves wave breaking offshore at larger depths (40% increase for the case with <i>n<sub>eq</sub></i> = 0.82), while it does not affect much the breaking height (4% was the largest difference). For very high <i>n<sub>eq</sub></i> (0.98 in the present study) and/or small <i>L<sub>CV</sub></i> (83% of the wavelength just offshore of the CV field in the present study), wave breaking may occur at depths smaller than in the non-vegetated situation due to increased wave shoaling over the corresponding CV fields. The undertow distribution is strongly modified and an increased wave setup (highest for <i>n<sub>eq</sub></i> = 0.82) is observed for all vegetated cases in comparison to the non-vegetated one. |
| first_indexed | 2024-03-11T06:21:08Z |
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| id | doaj.art-637a53aeeac44c8c87f7b2a1f80c1891 |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-11T06:21:08Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-637a53aeeac44c8c87f7b2a1f80c18912023-11-17T11:56:46ZengMDPI AGJournal of Marine Science and Engineering2077-13122023-02-0111351910.3390/jmse11030519Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous MediumIason A. Chalmoukis0Georgios A. Leftheriotis1Athanassios A. Dimas2Department of Civil Engineering, University of Patras, 26500 Patras, GreeceDepartment of Civil Engineering, University of Patras, 26500 Patras, GreeceDepartment of Civil Engineering, University of Patras, 26500 Patras, GreeceErosion and flooding are the main threats for most coastal regions. Nature-based solutions, such as coastal vegetation (CV) fields, have received significant attention in recent years because they effectively dissipate wave energy while maintaining biodiversity. In this study, a porous medium model was implemented in an in-house software to simulate the three-dimensional, two-phase (water/air) flow induced by wave propagation past CV fields. First, the model was validated against experimental measurements of wave propagation past a CV field on a horizontal bed. Then, the model was used to assess the influence on wave behaviour of the equivalent porosity, <i>n<sub>eq</sub></i>, and the cross-shore length, <i>L<sub>CV</sub></i>, of a CV field with a constant plant height on a beach with a constant bed slope. Results were obtained for the non-vegetated case (<i>n<sub>eq</sub></i> = 1) and five vegetated cases with different <i>n<sub>eq</sub></i> and <i>L<sub>CV</sub></i> values. It was found that decreasing <i>n<sub>eq</sub></i> moves wave breaking offshore at larger depths (40% increase for the case with <i>n<sub>eq</sub></i> = 0.82), while it does not affect much the breaking height (4% was the largest difference). For very high <i>n<sub>eq</sub></i> (0.98 in the present study) and/or small <i>L<sub>CV</sub></i> (83% of the wavelength just offshore of the CV field in the present study), wave breaking may occur at depths smaller than in the non-vegetated situation due to increased wave shoaling over the corresponding CV fields. The undertow distribution is strongly modified and an increased wave setup (highest for <i>n<sub>eq</sub></i> = 0.82) is observed for all vegetated cases in comparison to the non-vegetated one.https://www.mdpi.com/2077-1312/11/3/519coastal vegetationporous medium approachwave attenuationwave setupwave run-upNavier-Stokes equations |
| spellingShingle | Iason A. Chalmoukis Georgios A. Leftheriotis Athanassios A. Dimas Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium Journal of Marine Science and Engineering coastal vegetation porous medium approach wave attenuation wave setup wave run-up Navier-Stokes equations |
| title | Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium |
| title_full | Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium |
| title_fullStr | Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium |
| title_full_unstemmed | Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium |
| title_short | Large-Eddy Simulation of Wave Attenuation and Breaking on a Beach with Coastal Vegetation Modelled as Porous Medium |
| title_sort | large eddy simulation of wave attenuation and breaking on a beach with coastal vegetation modelled as porous medium |
| topic | coastal vegetation porous medium approach wave attenuation wave setup wave run-up Navier-Stokes equations |
| url | https://www.mdpi.com/2077-1312/11/3/519 |
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