Extreme waves induced by strong depth transitions: Fully nonlinear results

Viotti, Claudio; Dias, Frédéric

doi:10.1063/1.4880659

Cited by 63 publications

(59 citation statements)

References 17 publications

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“…Fortunately, the optical measurements allow us to extract statistical information continuously in space, rather than at a discrete set of positions. This capability is crucial for identifying regions of anomalous activity, as previous studies have suggested such regions to be highly localized [31]. While examining the complete distribution of η at a continuum of positions would prove impractical, the first few statistical moments provide useful proxies.…”

Section: Resultsmentioning

confidence: 99%

Anomalous wave statistics induced by abrupt depth change

2019

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Laboratory experiments reveal that variations in bottom topography can qualitatively alter the distribution of randomized surface waves. A normally-distributed, unidirectional wave field becomes highly skewed and non-Gaussian upon encountering an abrupt depth transition. A short distance downstream of the transition, wave statistics conform closely to a gamma distribution, affording simple estimates for skewness, kurtosis, and other statistical properties. Importantly, the exponential decay of the gamma distribution is much slower than Gaussian, signifying that extreme events occur more frequently. Under the conditions considered here, the probability of a rogue wave can increase by a factor of 50 or more. We also report on the surface-slope statistics and the spectral content of the waves produced in the experiments.1 A mechanism analogous to the BF instability can also arise in optical systems, giving rise to 'optical rogue waves' [27].

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Section: Resultsmentioning

confidence: 99%

Anomalous wave statistics induced by abrupt depth change

2019

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“…The computational domain becomes a uniform flat strip, more amenable to computations. A similar conformal mapping formulation has been used by Viotti et al, 6,7 but their underlying current is irrotational. In Viotti et al, 6 two examples are considered.…”

Section: Introductionmentioning

confidence: 99%

“…And finally an example with one supercritical stationary wave generation, due to the presence of a submerged triangular obstacle. In Viotti and Dias, 7 an initial random wave field is given and allowed to propagate toward a long shallower region, allowing for extreme wave formation. The scope of these interesting studies is different from ours.…”

Section: Introductionmentioning

confidence: 99%

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Rotational waves generated by current‐topography interaction

2019

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We study nonlinear free‐surface rotational waves generated through the interaction of a vertically sheared current with a topography. Equivalently, the waves may be generated by a pressure distribution along the free surface. A forced Korteweg–de Vries equation (fKdV) is deduced incorporating these features. The weakly nonlinear, weakly dispersive reduced model is valid for small amplitude topographies. To study the effect of gradually increasing the topography amplitude, the free surface Euler equations are formulated in the presence of a variable depth and a sheared current of constant vorticity. Under constant vorticity, the harmonic velocity component is formulated in a simplified canonical domain, through the use of a conformal mapping which flattens both the free surface as well as the bottom topography. Critical, supercritical, and subcritical Froude number regimes are considered, while the bottom amplitude is gradually increased in both the irrotational and rotational wave regimes. Solutions to the fKdV model are compared to those from the Euler equations. We show that for rotational waves the critical Froude number is shifted away from 1. New stationary solutions are found and their stability tested numerically.

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“…The fluid domain of each patch measures eight and three ship lengths in the x and y directions, respectively. Numerical beach as introduced in Viotti & Dias [45] is located at the downstream edge (negative x direction) of each patch, and the ship waves approaching downstream boundary are gradually damped and eventually eliminated. Moreover, in all computational cases, Hull 2 starts at the initial position of st/L = −3, and the overtaking process ends with st/L = 1.5.…”

Section: (B) Time-marching By Moving-patch Methodsmentioning

confidence: 99%

Experimental and numerical study of ship-to-ship interactions in overtaking manoeuvres

Yu¹,

Wang²,

Yeung³

2019

Proc. R. Soc. A.

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The study on close-quarter manoeuvring of vessels is of great importance for the safety and efficiency of maritime operations. In this paper, the hydrodynamic interactions between two vessels in moderate-speed overtaking manoeuvres are studied. Computational investigation by free-surface panel method is performed, and the results are assessed against experimental measurements from towing-tank model tests. The influences of overtaking speed and the speed difference between vessels on the hydrodynamic loads are studied. It is found that the free-surface deformation, on account of the blockage effects of the bodies, wave-making properties of the vessels, and the interference of unsteady wave patterns between the vessels, considerably affects the hydrodynamic interactions. In addition, it is also discovered that the influence from the unsteady heave and pitch motions of the hulls on the hydrodynamic loads can be non-negligible. Furthermore, it is found that the slower vessel to be overtaken generally experiences larger loads with more variation than the overtaking vessel. The loads on both vessels become more similar to those of a steady-state di-hull system when the speed difference between vessels is small.

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Extreme waves induced by strong depth transitions: Fully nonlinear results

Abstract: Articles you may be interested in Mechanical energy dissipation induced by sloshing and wave breaking in a fully coupled angular motion system. I. Theoretical formulation and numerical investigation Phys.

Cited by 63 publications

References 17 publications

Anomalous wave statistics induced by abrupt depth change

Anomalous wave statistics induced by abrupt depth change

Rotational waves generated by current‐topography interaction

Experimental and numerical study of ship-to-ship interactions in overtaking manoeuvres

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