Extreme waves in random crossing seas: Laboratory experiments and numerical simulations

Toffoli, Alessandro; Bitner‐Gregersen, Elzbieta M.; Osborne, A. R.; Serio, M.; Monbaliu, Jaak; Onorato, Miguel

doi:10.1029/2011gl046827

Cited by 89 publications

(70 citation statements)

References 18 publications

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“…Onorato et al (2006a) proposed a system of two coupled nonlinear Schrödinger equations (CNLS) to explain the formation of wave extremes in crossing seas (see also Shukla et al, 2006), showing that the second wave train advancing at a certain critical angle facilitates the modulational instability. These findings are validated by numerical simulations of the Euler equations, as well as by laboratory experiments (Onorato et al, 2010;Toffoli et al, 2011). It has also been found that the coefficient of kurtosis increases up to 40 • of crossing between the wave trains and then stabilizes, reaching a maximum between 40 and 60 • .…”

Section: P G Petrova and C Guedes Soares: Distributions Of Nonlinesupporting

confidence: 60%

“…These results actually confirm the fact that the large shift between the main directions of the component wave systems in a mixed sea suppresses the modulational instability. Consequently, one encounters smaller wave amplitudes and heights at the lowest probability levels of the distribution tails, as already reported for numerically simulated waves (Onorato et al, 2006a;Shukla et al, 2006;Onorato et al, 2010;Toffoli et al, 2011) for waves modelled from the second-order theory (Toffoli et al, 2006), or in laboratory experiments (Toffoli et al, 2011). The most favourable angles of crossing for the occurrence of large wave events are reported to be in the range between 10 and 40 • .…”

Section: Probability Distributions Of Wave Crests and Troughssupporting

confidence: 50%

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Distributions of nonlinear wave amplitudes and heights from laboratory generated following and crossing bimodal seas

Petrova

Soares

2014

Nat. Hazards Earth Syst. Sci.

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Abstract. This paper presents an analysis of the distributions of nonlinear crests, troughs and heights of deep water waves from mixed following sea states generated mechanically in an offshore basin and compares with previous results for mixed crossing seas from the same experiment. The random signals at the wavemaker in both types of mixed seas are characterized by bimodal spectra following the model of Guedes Soares (1984). In agreement with the Benjamin-Feir mechanism, the high-frequency spectrum shows a decrease in the peak magnitude and downshift of the peak with the distance, as well as reduction of the tail. The observed statistics and probabilistic distributions exhibit, in general, increasing effects of third-order nonlinearity with the distance from the wavemaker. However, this effect is less pronounced in the wave systems with two following wave trains than in the crossing seas, given that they have identical initial characteristics of the bimodal spectra. The relevance of third-order effects due to free modes only is demonstrated and assessed by excluding the vertically asymmetric distortions induced by bound wave effects of second and third order. The fact that for records characterized by relatively large coefficient of kurtosis, the empirical distributions for the non-skewed profiles continue deviating from the linear predictions, corroborate the relevance of free wave interactions and thus the need of using higher-order models for the description of wave data.

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Section: P G Petrova and C Guedes Soares: Distributions Of Nonlinesupporting

confidence: 60%

Section: Probability Distributions Of Wave Crests and Troughssupporting

confidence: 50%

Distributions of nonlinear wave amplitudes and heights from laboratory generated following and crossing bimodal seas

Petrova

Soares

2014

Nat. Hazards Earth Syst. Sci.

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“…Onorato et al (2009) and Toffoli et al (2010) performed experiments and numerical analysis of irregular crossing waves, observing a direct relationship between crossing angle and kurtosis, an indicator of the probability of freak wave occurrence. All of the experimental studies that we are aware of have been limited to small degrees of directional spreading and have not observed the formation of a set-up, with the exception of Toffoli et al (2011), who did conduct experiments with crossing wave systems at crossing angles up to 40…”

Section: Introductionmentioning

confidence: 99%

The set-down and set-up of directionally spread and crossing surface gravity wave groups

et al. 2017

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For sufficiently directionally spread surface gravity wave groups, the set-down of the wave-averaged free surface, first described by Longuet-Higgins and Stewart (J. Fluid Mech. vol. 13, 1962, pp. 481-504), can turn into a set-up. Using a multiple-scale expansion for two crossing wave groups, we examine the structure and magnitude of this wave-averaged set-up, which is part of a crossing wave pattern that behaves as a modulated partial standing wave: in space, it consists of a rapidly varying standing-wave pattern slowly modulated by the product of the envelopes of the two groups; in time, it grows and decays on the slow time scale associated with the translation of the groups. Whether this crossing wave pattern actually enhances the surface elevation at the point of focus depends on the phases of the linear wave groups, unlike the set-down, which is always negative and inherits the spatial structure of the underlying envelope(s). We present detailed laboratory measurements of the wave-averaged free surface, examining both single wave groups, varying the degree of spreading from small to very large, and the interaction between two wave groups, varying both the degree of spreading and the crossing angle between the groups. In both cases, we find good agreement between the experiments, our simple expressions for the set-down and set-up, and existing second-order theory based on the component-by-component interaction of individual waves with different frequencies and directions. We predict and observe a set-up for wave groups with a Gaussian angular amplitude distribution with standard deviations of above 30-40• (21-28 • for energy spectra), which is relatively large for realistic sea states, and for crossing sea states with angles of separation of 50-70• and above, which are known to occur in the ocean.

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“…Nowadays, the study methods on rogue waves mainly focus on theoretical analysis (Onorato et al, 2006a, b), numerical simulation (Tao et al, , 2012a, physical experiment (Toffoli et al, 2010(Toffoli et al, , 2011) and field observations. Some key advances were reviewed by Dysthe et al (2008) and Kharif et al (2009).…”

Section: Introductionmentioning

confidence: 99%

A preliminary investigation of rogue waves off the Jiangsu coast, China

Wang

Tao

Zheng

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Due to the potential disasters induced by rogue waves, research in this field has increased rapidly in the last 2 decades. However, there are still a lot of open questions left, including some classic ones, such as whether the rogues waves are just rare events or not. One of the key reasons is that not enough of the observed rogue waves have been investigated. China has a wide sea area, but none of the research has addressed the observed rogue waves. In the present study, 1 year of observed wave data from Jiangsu coastal area, China, are analyzed. It is found that rogue waves are present, although the wave heights are not very large; furthermore, the probability of their occurrence is similar to the Rayleigh distribution prediction, due to the local silty coastal topography. The characteristics of rouge waves are investigated and the results indicate that a new type of rogue wave may exist.

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Extreme waves in random crossing seas: Laboratory experiments and numerical simulations

Cited by 89 publications

References 18 publications

Distributions of nonlinear wave amplitudes and heights from laboratory generated following and crossing bimodal seas

Distributions of nonlinear wave amplitudes and heights from laboratory generated following and crossing bimodal seas

The set-down and set-up of directionally spread and crossing surface gravity wave groups

A preliminary investigation of rogue waves off the Jiangsu coast, China

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