Occurrence of Extreme Waves in Finite Water Depth

Fernández, Leandro; Onorato, Miguel; Monbaliu, Jaak; Toffoli, Alessandro

doi:10.1007/978-3-319-21575-4_3

Cited by 5 publications

(5 citation statements)

References 43 publications

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“…These conclusions were supported by Toffoli et al [36] who used a HOSM to simulate random wave fields correct to a third order of wave steepness. Similar results have been obtained in numerical and experimental investigations of random sea states with large directional spreading [37]. By contrast, field data from Lake George, Australia included in the same study indicate notable amplifications beyond the second-order crest height statistics in the steepest sea states.…”

Section: Introductionsupporting

confidence: 85%

Laboratory investigation of crest height statistics in intermediate water depths

2019

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This paper concerns the statistical distribution of the crest heights associated with surface waves in intermediate water depths. The results of a new laboratory study are presented in which data generated in different experimental facilities are used to establish departures from commonly applied statistical distributions. Specifically, the effects of varying sea-state steepness, effective water depth and directional spread are investigated. Following an extensive validation of the experimental data, including direct comparisons to available field data, it is shown that the nonlinear amplification of crest heights above second-order theory observed in steep deep water sea states is equally appropriate to intermediate water depths. These nonlinear amplifications increase with the sea-state steepness and reduce with the directional spread. While the latter effect is undoubtedly important, the present data confirm that significant amplifications above second order (5–10%) are observed for realistic directional spreads. This is consistent with available field data. With further increases in the sea-state steepness, the dissipative effects of wave breaking act to reduce these nonlinear amplifications. While the competing mechanisms of nonlinear amplification and wave breaking are relevant to a full range of water depths, the relative importance of wave breaking increases as the effective water depth reduces.

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Section: Introductionsupporting

confidence: 85%

Laboratory investigation of crest height statistics in intermediate water depths

2019

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“…That said, for finiteamplitude waves, Benney andRoskes (1969), McLean (1982), Toffoli et al (2013) showed that the MI, as a combination of quartet resonant wave interaction and wave nonlinearity, can occur even in water regions where kh≲1:36 , when the waves are subject to oblique perturbations. The directional spreading and wave dissipation in random sea states in uniform and finite water depth have been found to lead to considerable deviations from normal statistics (see, e.g., Fernandez et al, 2015;Karmpadakis et al, 2019, among others), while numerical simulations based on the high-order spectral method (HOSM) have indicated the emergence of significant deviations from normal statistics in random directional sea states in the absence of breaking dissipation and independently of the significance of directional spreading of wave spectra in the same uniform depth conditions (Toffoli et al, 2009).…”

Section: Physical Mechanisms and Modelingmentioning

confidence: 99%

On the formation of coastal rogue waves in water of variable depth

Chabchoub¹

2023

Camb. prisms Coast. futures

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Wave transformation is an intrinsic dynamic process in coastal areas. An essential part of this process is the variation of water depth, which plays a dominant role in the propagation features of water waves, including a change in wave amplitude during shoaling and de-shoaling, breaking, celerity variation, refraction and diffraction processes. Fundamental theoretical studies have revolved around the development of analytical frameworks to accurately describe such shoaling processes and wave group hydrodynamics in the transition between deep- and shallow-water conditions since the 1970s. Very recent pioneering experimental studies in state-of-the-art water wave facilities provided proof of concept validations and improved understanding of the formed extreme waves’ physical characteristics and statistics in variable water depth. This review recaps the related most significant theoretical developments and groundbreaking experimental advances, which have particularly thrived over the last decade.

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“…As an example, nonlinear simulations, experiments, and theoretical works have been conducted to try to predict the evolution of kurtosis in different contexts (Onorato et al 2004(Onorato et al , 2005(Onorato et al , 2006Toffoli et al 2009;Shemer and Sergeeva 2009;Fernandez et al 2014Fernandez et al , 2016Janssen2003;Janssen and Bidlot 2009;Fedele 2015). However, as far as we know, existing works in a fully nonlinear context only consider one influencing factor, either BFI (Onorato et al 2004(Onorato et al , 2005(Onorato et al , 2006Shemer and Sergeeva 2009) or relative water depth k p h (Toffoli et al 2009;Fernandez et al 2014Fernandez et al , 2016, and exhibit a limited range of variations. There is consequently a need in providing a thorough study of the effects of both parameters over a large range for unidirectional irregular sea states.…”

Section: Single-peak Spectrummentioning

confidence: 99%

Statistics of long-crested extreme waves in single and mixed sea states

Wang

Liu

et al. 2020

Ocean Dynamics

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Most of the studies on extreme waves are focused on the systems with single-peak wave spectra. However, according to the statistics of occurrence, the bimodal spectral system is also frequent in real sea conditions. In order to summarize the statistics of extreme waves, irregular wave trains under single-peak and bimodal spectra for long durations are simulated in this paper, based on a two-dimensional High Order Spectral (HOS) numerical wave tank. A large number of configurations have been tested under unimodal and bimodal spectra. The investigation on the wave trains under single-peak spectrum indicates that although in conditions often referred as deep water (k p h > π), the relative water depth has a significant influence on the probabilities of occurrence of extreme waves. A detailed analysis of the combined effect of Benjamin-Feir Index (BFI) and relative water depth is provided. However, the situation is more complex in real sea conditions, which may exhibit multimodal spectra. We focus in this study on long-crested bimodal spectra characterized by the same significant wave height H s and mean zero-crossing period T z of the sea states as the single-peak spectrum. The wave conditions under bimodal spectrum present milder extreme wave statistics than those under single-peak spectrum. In addition, mixed ocean systems with equivalent energy distribution (i.e., Sea-Swell Energy Ratio (SSER) is close to 1.0) and larger separation between partitions (i.e., Intermodal Distance (ID) > 0.10) are the less prominent to extreme waves appearance. The comparison of the mixed sea states and the corresponding single independent systems demonstrates that the complexity of the underlying physics of a given sea state (for instance the presence of modulational instability or other nonlinear process) cannot be deduced by an analysis limited to the statistical content of the combined sea state. The wave energy being distributed among frequencies plays a major role. Additionally, Gram-Charlier distribution can accurately predict the probability of large waves (1.5 < H/H s < 2.0) compared to the MER distribution, but it underestimates the statistics of the wave height distribution when H/H s is larger than 2.0 for both single-peak and bimodal states.

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Occurrence of Extreme Waves in Finite Water Depth

Cited by 5 publications

References 43 publications

Laboratory investigation of crest height statistics in intermediate water depths

Laboratory investigation of crest height statistics in intermediate water depths

On the formation of coastal rogue waves in water of variable depth

Statistics of long-crested extreme waves in single and mixed sea states

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