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| Titel |
Effect of higher order nonlinearity, directionality and finite water depth on wave statistics: Comparison of laboratory experiments, field data and numerical simulations. |
| VerfasserIn |
Leandro Fernández, Miguel Onorato, Jaak Monbaliu, Alessandro Toffoli |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101403
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| Publikation (Nr.) |
 EGU/EGU2015-534.pdf |
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| Zusammenfassung |
| This research is focused on the study of nonlinear evolution of irregular wave fields in water
of arbitrary depth by comparing laboratory experiments, field measurements and numerical
simulations. It is now well accepted that modulational instability, known as one of the main
mechanisms for the formation of rogue waves, induces strong departures from Gaussian
statistics and second order based statistics. However, whereas non-Gaussian properties are
remarkable when wave fields follow one direction of propagation over an infinite water depth,
wave statistics only weakly deviate from Gaussianity when waves spread over a range of
different directions. Over finite water depth, furthermore, wave instability attenuates overall
and eventually vanishes for relative water depths as low as kh = 1.36 (where k is the
wavenumber of the dominant waves and h the water depth). Recent experimental results,
nonetheless, seem to indicate that oblique perturbations are capable of triggering and
sustaining modulational instability even if kh < 1.36. In this regard, the aim of
this research is to understand whether the combined effect of directionality and
finite water depth has a significant effect on wave statistics and particularly on
the occurrence of extremes. For this purpose, laboratory experiments in a large
wave basin, numerical experiments solving the Euler equation of motion with the
Higher Order Spectral Method (HOSM) and field experiments at the Lake George
experimental site (Australia) have been compared to assess the role of third order
nonlinearity, and particularly modulational instability, on wave statistics. Herein, we
present a comparative analysis of the statistical properties (i.e. density function of
the surface elevation and its statistical moments skewness and kurtosis) between
laboratory experiments, simulations and in-situ data which provides a confrontation
between the numerical results and real observations in laboratory and field conditions. |
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