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Showing papers on "Rogue wave published in 1990"


Book ChapterDOI
R. G. Dean1
TL;DR: In this paper, a possible explanation for the occurrence of freak waves is proposed, which is defined as waves with larger heights than expected based on the Rayleigh distribution, and the suggested cause is due to nonlinearities of superposition of waves which are not accounted for in Rayleigh, and it is shown that the combined wave height increases by more than the sum of the fundamental components.
Abstract: A possible explanation is proposed for the occurrence of freak waves, which are defined as waves with larger heights than expected based on the Rayleigh distribution. The suggested cause is due to nonlinearities of superposition of waves which are not accounted for in the Rayleigh distribution. When two waves combine, if their fundamental components add linearly, it can be shown that the combined wave height increases by more than the sum of the fundamental components. The argument does not address the correctness of linear addition of the fundamental components nor does it include energy closure. An example is presented illustrating the concept.

102 citations


Book ChapterDOI
TL;DR: In this paper, the authors analyzed the record of extreme single waves recorded on the Danish Continental Shelf and showed that these waves do not belong to the traditional short term statistical distributions used for ocean waves.
Abstract: Prototype records of extreme single waves recorded on the Danish Continental Shelf have been analysed in detail. Statistical calculations show that these waves do not belong to the traditional short term statistical distributions used for ocean waves. The waves are too high, too asymmetric and too steep.

75 citations


Book ChapterDOI
TL;DR: In this paper, the authors compared wave speeds and wave heights with the Rayleigh model and linear numerical wave data, and found that wave speeds are asymmetric with higher crests and shallow troughs than predicted by linear theory.
Abstract: Large waves in experimental model scale random wave trains are investigated. Statistical distributions of crest heights, troughs and peak-to-peak wave heights are compared to the Rayleigh model and to linear numerical wave data. Wave heights are seen to agree well with the Rayleigh distribution. The largest individual waves from the experiment show asymmetric behaviour with higher crests and more shallow troughs than predicted by the linear theory. This is seen both from Weibull distribution plots and from wave profiles of individual large waves in the time domain. Particle velocities in extreme waves, estimated by linear transformations of wave elevation measurements, are particularly asymmetric and peaked. Proper design rules for extreme waves should be further developed. More knowledge on full scale waves must form a central part of this development.

19 citations


Book ChapterDOI
01 Jan 1990
TL;DR: In this article, the authors discuss the possibility of waves breaking in deep-water but details are only given in the context of wave tank simulations, and conventional measurements at sea do not distinguish broken from unbroken waves.
Abstract: Presentations at the workshop have included discussion of waves breaking in deep-water but details are only given in the context of wave tank simulations. Conventional measurements at sea do not distinguish broken from unbroken waves.

2 citations


Book ChapterDOI
R. G. Dean1
01 Jan 1990
TL;DR: The state of the art of water wave kinematic prediction and understanding and areas of needed research are presented and recommendations are made for the continuation of research in: theory, numerical developments and laboratory and field research.
Abstract: A review is presented of the state of the art of water wave kinematic prediction and understanding and areas of needed research. Existing capabilities to predict kinematics in the laboratory under regular wave conditions appear to be within the accuracy (≈ 5%) of inherent errors in the measurements. Recent contributions in numerical techniques for regular waves over a sloping bottom also appear to yield similar accuracy up to the point of wave breaking. Predictive capability irregular waves within the laboratory environment appears adequate except in the case where strong nonlinearities exist, such as near the free surface. A proven methodology does not exist to address the general problem of interaction of waves with a current of arbitrary vorticity distribution. In nature, waves are much more complicated than can be generated in most laboratory facilities and the conditions much less controlled; thus the state of the art is less satisfying than for laboratory conditions and the associated research needs are greater. Research needs include a nonlinear and directional wave theory to be more representative of extreme conditions in nature. Ultimately, the theory should encompass the presence of an arbitrary three-dimensional current field. The magnitude and kinematic significance of the second-order forced waves, usually most pronounced in narrow spectra of limited directional spreading, appear to be significant and should be incorporated into design procedures. Wave systems generated by concentrated and complex wind fields have a high degree of directionality which may have significance for the extreme waves, both due to the directional content of the kinematics and also due to the local three-dimensionality of the sea surface. Because of the significance of freak waves to design, their causes should be investigated further and design procedures developed. Recommendations are made for the continuation of research in: theory, numerical developments and laboratory and field research. Due to the inherent difficulties in conducting field research and the fact that the first order processes are well-understood, these programs should be well-coordinated with a broad range of interests involved in the planning and assurance that the data are of high quality resulting from frequent instrument calibration and validation of the resulting data as it becomes available.

1 citations


Book ChapterDOI
TL;DR: In this paper, the authors identify two topics where a scientific approach is needed in order to achieve a better understanding of phenomena and better prediction, and propose a method to improve seakeeping capabilities of vessels.
Abstract: The Labrador Sea Extreme Waves Experiment “LEWEX”, is a comprehensive international effort, with the purpose to improve seakeeping capabilities of vessels. Two topics are identified where a scientific approach is needed in order to achieve a better understanding of phenomena and better prediction. These are: