Three-dimensional wave breaking.

Autor: McAllister ML; Department of Engineering Science, University of Oxford, Oxford, UK. mark.mcallister@trinity.ox.ac.uk., Draycott S; School of Engineering, University of Manchester, Manchester, UK., Calvert R; School of Engineering, University of Edinburgh, Edinburgh, UK., Davey T; School of Engineering, University of Edinburgh, Edinburgh, UK., Dias F; School of Mathematics and Statistics, University College Dublin, Dublin, Ireland.; Université Paris-Saclay, CNRS, ENS Paris-Saclay, Centre Borelli, Paris, France., van den Bremer TS; Department of Engineering Science, University of Oxford, Oxford, UK.; Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands.
Jazyk: angličtina
Zdroj: Nature [Nature] 2024 Sep; Vol. 633 (8030), pp. 601-607. Date of Electronic Publication: 2024 Sep 18.
DOI: 10.1038/s41586-024-07886-z
Abstrakt: Although a ubiquitous natural phenomenon, the onset and subsequent process of surface wave breaking are not fully understood. Breaking affects how steep waves become and drives air-sea exchanges 1 . Most seminal and state-of-the-art research on breaking is underpinned by the assumption of two-dimensionality, although ocean waves are three dimensional. We present experimental results that assess how three-dimensionality affects breaking, without putting limits on the direction of travel of the waves. We show that the breaking-onset steepness of the most directionally spread case is double that of its unidirectional counterpart. We identify three breaking regimes. As directional spreading increases, horizontally overturning 'travelling-wave breaking' (I), which forms the basis of two-dimensional breaking, is replaced by vertically jetting 'standing-wave breaking' (II). In between, 'travelling-standing-wave breaking' (III) is characterized by the formation of vertical jets along a fast-moving crest. The mechanisms in each regime determine how breaking limits steepness and affects subsequent air-sea exchanges. Unlike in two dimensions, three-dimensional wave-breaking onset does not limit how steep waves may become, and we produce directionally spread waves 80% steeper than at breaking onset and four times steeper than equivalent two-dimensional waves at their breaking onset. Our observations challenge the validity of state-of-the-art methods used to calculate energy dissipation and to design offshore structures in highly directionally spread seas.
(© 2024. The Author(s).)
Databáze: MEDLINE
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