The set-down and set-up of directionally spread and crossing surface gravity wave groups in severe north sea storms

Mark L. McAllister, Thomas A.A. Adcock, Ton S.Vanden Bremer, Paul H. Taylor

Research output: Contribution to conferenceAbstract

Abstract

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.

Original languageEnglish
DOIs
Publication statusPublished - 1 Jan 2018
EventASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2018 - Madrid Marriott Auditorium Hotel & Conference Centre, Madrid, Spain
Duration: 17 Jun 201822 Jun 2018
https://www.asme.org/events/omae

Conference

ConferenceASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2018
Abbreviated titleOMAE 2018
CountrySpain
CityMadrid
Period17/06/1822/06/18
Internet address

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