Non-Gaussian properties of second-order wave orbital velocity

Alberello, Alberto, Chabchoub, Amin, Gramstad, Odin, Babanin, Alexander V. and Toffoli, Alessandro (2016) Non-Gaussian properties of second-order wave orbital velocity. Coastal Engineering, 110. pp. 42-49. ISSN 0378-3839

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Abstract

A stochastic second-order wave model is applied to assess the statistical properties of wave orbital velocity in random sea states below the water surface. Directional spreading effects as well as the dependency of the water depth are investigated by means of a Monte-Carlo approach. Unlike for the surface elevation, sub-harmonics dominate the second-order contribution to orbital velocity. We show that a notable set-down occurs for the most energetic and steepest groups. This engenders a negative skewness in the temporal evolution of the orbital velocity. A substantial deviation of the upper and lower tails of the probability density function from the Gaussian distribution is noticed; velocities are faster below the wave trough and slower below the wave crest when compared with linear theory predictions. Second-order nonlinearity effects strengthen with reducing the water depth, while weaken with the broadening of the wave spectrum. The results are confirmed by laboratory data. Corresponding experiments have been conducted in a large wave basin taking into account the directionality of the wave field. As shown, laboratory data are in very good agreement with the numerical prediction.

Item Type: Article
Additional Information: Funding Information: This work was supported by the Swinburne University of Technology Postgraduate Research Award (SUPRA). Experiments were funded by the E.U. 7 th Framework Programme through the Integrated Infrastructure Initiative HYDRALAB IV (Contract No. 022441 ). A.A. and A.T. thank Miguel Onorato for valuable discussions on wave orbital motions. A.C. acknowledges support from the Burgundy Region and The Association of German Engineers (VDI). A.C. is an International Research Fellow of the Japan Society for the Promotion of Science (JSPS). Publisher Copyright: © 2016 Elsevier B.V.
Uncontrolled Keywords: second-order,wave orbital motion,wave statistics,environmental engineering,ocean engineering ,/dk/atira/pure/subjectarea/asjc/2300/2305
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Depositing User: LivePure Connector
Date Deposited: 13 Nov 2021 01:51
Last Modified: 15 Nov 2021 01:43
URI: https://ueaeprints.uea.ac.uk/id/eprint/82086
DOI: 10.1016/j.coastaleng.2016.01.001

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