The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms
Recent work by McAllister et al. (2018) [1] has experimentally confirmed that the set-down of the wave-averaged free surface, first described by Longuet-Higgins and Stewart (1962) [2], can turn into a set-up when wave groups are sufficiently spread or cross at large angles. Experimental results were...
| Main Authors: | , , , |
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| Format: | Conference item |
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American Society of Mechanical Engineers
2017
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| _version_ | 1797067174521602048 |
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| author | McAllister, M Adcock, T van den Bremer, T Taylor, P |
| author_facet | McAllister, M Adcock, T van den Bremer, T Taylor, P |
| author_sort | McAllister, M |
| collection | OXFORD |
| description | Recent work by McAllister et al. (2018) [1] has experimentally confirmed that the set-down of the wave-averaged free surface, first described by Longuet-Higgins and Stewart (1962) [2], can turn into a set-up when wave groups are sufficiently spread or cross at large angles. Experimental results were shown to agree well with second-order theory, including frequency-sum and frequency-difference terms, where the latter are responsible for the wave-averaged free surface. In this paper, we review these experimental results and examine theoretically the magnitude of the wave-averaged free surface in realistic extreme North Sea conditions. Specifically, we examine the role of the shape of the spectrum, water depth, and the relative magnitude of the peak frequencies of the two crossing groups. We find that having a realistic spectrum (JONSWAP vs. Gaussian) considerably enhances the magnitude of the second-order contribution, the total second-order signal increases with decreasing depth and can display a maximum provided the water depth is shallow enough for small to moderate degrees of spreading or crossing angles and is larger for spectral peaks that are further apart. |
| first_indexed | 2024-03-06T21:52:35Z |
| format | Conference item |
| id | oxford-uuid:4bcf7a71-e037-44ec-ac98-7d08dcffcd09 |
| institution | University of Oxford |
| last_indexed | 2024-03-06T21:52:35Z |
| publishDate | 2017 |
| publisher | American Society of Mechanical Engineers |
| record_format | dspace |
| spelling | oxford-uuid:4bcf7a71-e037-44ec-ac98-7d08dcffcd092022-03-26T15:45:47ZThe set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea stormsConference itemhttp://purl.org/coar/resource_type/c_5794uuid:4bcf7a71-e037-44ec-ac98-7d08dcffcd09Symplectic Elements at OxfordAmerican Society of Mechanical Engineers2017McAllister, MAdcock, Tvan den Bremer, TTaylor, PRecent work by McAllister et al. (2018) [1] has experimentally confirmed that the set-down of the wave-averaged free surface, first described by Longuet-Higgins and Stewart (1962) [2], can turn into a set-up when wave groups are sufficiently spread or cross at large angles. Experimental results were shown to agree well with second-order theory, including frequency-sum and frequency-difference terms, where the latter are responsible for the wave-averaged free surface. In this paper, we review these experimental results and examine theoretically the magnitude of the wave-averaged free surface in realistic extreme North Sea conditions. Specifically, we examine the role of the shape of the spectrum, water depth, and the relative magnitude of the peak frequencies of the two crossing groups. We find that having a realistic spectrum (JONSWAP vs. Gaussian) considerably enhances the magnitude of the second-order contribution, the total second-order signal increases with decreasing depth and can display a maximum provided the water depth is shallow enough for small to moderate degrees of spreading or crossing angles and is larger for spectral peaks that are further apart. |
| spellingShingle | McAllister, M Adcock, T van den Bremer, T Taylor, P The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms |
| title | The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms |
| title_full | The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms |
| title_fullStr | The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms |
| title_full_unstemmed | The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms |
| title_short | The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe North Sea storms |
| title_sort | set down and set up of directionally spread and crossing surface gravity wave groups in severe north sea storms |
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