Focusing wave group on a current of finite depth

Merkoune, Djalal; Touboul, Julien; Abcha, Nizar; Mouazé, Dominique; Ezersky, Alexander

doi:10.5194/nhess-13-2941-2013

Cited by 15 publications

(15 citation statements)

References 19 publications

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“…Full details of the implementation can be found in Touboul and Kharif (2010). The method has already been implemented and used successfully in the framework of focusing wave groups in the presence of uniform current (Touboul et al 2007;Merkoune et al 2013). …”

Section: Methodsmentioning

confidence: 99%

“…If such mechanism was widely studied in the context of rogue waves formation (Kharif et al 2001;Johannessen and Swan 2003), it is known to be significantly influenced by currents (Touboul et al 2007;Merkoune et al 2013) or wind (Kharif et al 2008). To the best of our knowledge, there is no study which concerns the dynamic of steep wave events due to dispersive focusing in the presence of vorticity.…”

Section: Introductionmentioning

confidence: 95%

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Effect of vorticity on the generation of rogue waves due to dispersive focusing

Touboul

Kharif

2016

Nat Hazards

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The kinematic and dynamic of steep two-dimensional focusing wave trains on a shearing flow in deep water are investigated analytically and numerically. In the absence of waves, the vorticity due to the vertical gradient of the horizontal current velocity is assumed constant. A linear kinematic model based on the spatio-temporal evolution of the frequency is derived, predicting the focusing distance and time of a chirped wave packet in the presence of constant vorticity. Furthermore, a linear model, based on a Fourier integral, is used to describe the evolution of the free surface on shearing current. To compute the fully nonlinear evolution of the wave group in the presence of vorticity, a new numerical model, based on a BIEM approach, is developed. On the basis of these different approaches, the role of constant vorticity on rogue wave occurrence is analysed. Two main resultsare obtained: (1) the linear behaviour expected in the presence of constant vorticity is significantly different from what is commonly expected in the presence of constant current and (2) the nonlinear effects are found to be of significant influence in the case at hand

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Effect of vorticity on the generation of rogue waves due to dispersive focusing

Touboul

Kharif

2016

Nat Hazards

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“…Afterwards, the long waves will be in front of the short waves and the amplitude of the wave train will decrease (Kharif and Pelinovsky, 2003). This mechanism is observed in the type of dispersive focusing waves which are often used in hydrodynamic laboratories (Merkoune et al, 2013;Brown and Jensen, 2001;Clauss, 2002;Shemer et al, 2007Shemer et al, , 2005Grue et al, 2003). In random waves, this mechanism could also trigger a freak wave, but it is not as clear as in the dispersive focusing case.…”

Section: Introductionmentioning

confidence: 99%

Localized coherence of freak waves

Latifah

Groesen

2016

Nonlin. Processes Geophys.

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Abstract. This paper investigates in detail a possible mechanism of energy convergence leading to freak waves. We give examples of a freak wave as a (weak) pseudo-maximal wave to illustrate the importance of phase coherence. Given a time signal at a certain position, we identify parts of the time signal with successive high amplitudes, so-called group events, that may lead to a freak wave using wavelet transform analysis. The local coherence of the critical group event is measured by its time spreading of the most energetic waves. Four types of signals have been investigated: dispersive focusing, normal sea condition, thunderstorm condition and an experimental irregular wave. In all cases presented in this paper, it is shown that a high correlation exists between the local coherence and the appearance of a freak wave. This makes it plausible that freak waves can be developed by local interactions of waves in a wave group and that the effect of waves that are not in the immediate vicinity is minimal. This indicates that a local coherence mechanism within a wave group can be one mechanism that leads to the appearance of a freak wave.

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“…Afterwards, the long waves will be in front of the short waves and the amplitude of the wave train will decrease (Kharif and Pelinovsky, 2003). This mechanism is observed in the type of dispersive focusing waves which are often used in hydrodynamic laboratories (Merkoune et al, 2013;Brown and Jensen, 2001;Clauss, 2002;Shemer et al, 2007Shemer et al, , 2005; Grue et al, 2003). In random waves, this mechanism could also trigger a freak wave, but it is not as clear as in the dispersive focusing case.…”

Section: Introductionmentioning

confidence: 99%

Comment to referee 2

Latifah¹

2016

View full text Add to dashboard Cite

This paper investigates in detail a possible mechanism of energy convergence leading to freak waves. We give examples of a freak wave as a (weak) pseudo-maximal wave to illustrate the importance of phase coherence. Given a time signal at a certain position, we identify parts of the time signal with successive high amplitudes, so-called group events, that may lead to a freak wave using wavelet transform analysis. The local coherence of the critical group event is measured by its time spreading of the most energetic waves. Four types of signals have been investigated: dispersive focusing, normal sea condition, thunderstorm condition and an experimental irregular wave. In all cases presented in this paper, it is shown that a high correlation exists between the local coherence and the appearance of a freak wave. This makes it plausible that freak waves can be developed by local interactions of waves in a wave group and that the effect of waves that are not in the immediate vicinity is minimal. This indicates that a local coherence mechanism within a wave group can be one mechanism that leads to the appearance of a freak wave.

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Focusing wave group on a current of finite depth

Cited by 15 publications

References 19 publications

Effect of vorticity on the generation of rogue waves due to dispersive focusing

Effect of vorticity on the generation of rogue waves due to dispersive focusing

Localized coherence of freak waves

Comment to referee 2

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