Experimental study of freak wave impacts on a tension-leg platform
TL;DR: In this paper, the authors investigated the freak wave impinging on a tension-leg platform through wave flume experiments and found that although applying less intensive local impact pressures as compared to the highly breaking freak wave, the slightly-breaking or non-breaking freak wave imposes the same level of adverse effect on the platform's global stability in terms of motions and tether forces.
About: This article is published in Marine Structures.The article was published on 2020-11-01. It has received 9 citations till now. The article focuses on the topics: Wave flume & Rogue wave.
Citations
More filters
TL;DR: In this paper , the expected freak wave is firstly embedded in an irregular wave train and then transformed into frequency domain by Fast Fourier Transform (FFT), which is helpful to investigate the mechanism of freak wave-structures interaction in deep.
9 citations
TL;DR: In this article , a high-fidelity CFD solver was adopted to obtain the parameters for each harmonic response of a floating offshore wind turbine (FOWT) in extreme marine environment.
9 citations
TL;DR: In this paper, the effects of the energy ratio of the focused wave train, number of constituent waves, and parameters of the JONSWAP wave spectrum on the generation probability of freak waves are studied, and the generator probability of the freak wave is fitted by a Γ cumulative probability density function.
9 citations
TL;DR: In this article , the effects of the air gap on wave actions and platform responses on oceanic floating platforms were investigated. But the authors focused on two air-gap conditions (i.e., 0.35 H c and 0.2 H c), where H c is the height of the platform column.
6 citations
TL;DR: In this article , the slamming pressure characteristics of a typical floating wind turbine under freak waves are studied by numerical simulation and experiment using the computational fluid dynamics (CFD) method, which is used to establish the numerical tank.
3 citations
References
More filters
TL;DR: In this article, a number of ases in which these equations reduce to a one dimensional nonlinear Schrodinger (NLS) equation are enumerated, and several analytical solutions of NLS equations are presented, with discussion of their implications for describing the propagation of water waves.
Abstract: Equations governing modulations of weakly nonlinear water waves are described. The modulations are coupled with wave-induced mean flows except in the case of water deeper than the modulation length scale. Equations suitable for water depths of the order the modulation length scale are deduced from those derived by Davey and Stewartson [5] and Dysthe [6]. A number of ases in which these equations reduce to a one dimensional nonlinear Schrodinger (NLS) equation are enumerated.Several analytical solutions of NLS equations are presented, with discussion of some of their implications for describing the propagation of water waves. Some of the solutions have not been presented in detail, or in convenient form before. One is new, a “rational” solution describing an “amplitude peak” which is isolated in space-time. Ma's [13] soli ton is particularly relevant to the recurrence of uniform wave trains in the experiment of Lake et al.[10].In further discussion it is pointed out that although water waves are unstable to three-dimensional disturbances, an effective description of weakly nonlinear two-dimensional waves would be a useful step towards describing ocean wave propagation.
1,318 citations
TL;DR: A review of physical mechanisms of the rogue wave phenomenon is given in this article, where the authors demonstrate that freak waves may appear in deep and shallow waters and demonstrate that these mechanisms remain valid but should be modified.
Abstract: A review of physical mechanisms of the rogue wave phenomenon is given. The data of marine observations as well as laboratory experiments are briefly discussed. They demonstrate that freak waves may appear in deep and shallow waters. Simple statistical analysis of the rogue wave probability based on the assumption of a Gaussian wave field is reproduced. In the context of water wave theories the probabilistic approach shows that numerical simulations of freak waves should be made for very long times on large spatial domains and large number of realizations. As linear models of freak waves the following mechanisms are considered: dispersion enhancement of transient wave groups, geometrical focusing in basins of variable depth, and wave-current interaction. Taking into account nonlinearity of the water waves, these mechanisms remain valid but should be modified. Also, the influence of the nonlinear modulational instability (Benjamin–Feir instability) on the rogue wave occurence is discussed. Specific numerical simulations were performed in the framework of classical nonlinear evolution equations: the nonlinear Schrodinger equation, the Davey–Stewartson system, the Korteweg–de Vries equation, the Kadomtsev–Petviashvili equation, the Zakharov equation, and the fully nonlinear potential equations. Their results show the main features of the physical mechanisms of rogue wave phenomenon.
962 citations
TL;DR: This work presents the first experimental results with observations of the Peregrine soliton in a water wave tank, and proposes a new approach to modeling deep water waves using the nonlinear Schrödinger equation.
Abstract: The conventional definition of rogue waves in the ocean is that their heights, from crest to trough, are more than about twice the significant wave height, which is the average wave height of the largest one-third of nearby waves. When modeling deep water waves using the nonlinear Schr\"odinger equation, the most likely candidate satisfying this criterion is the so-called Peregrine solution. It is localized in both space and time, thus describing a unique wave event. Until now, experiments specifically designed for observation of breather states in the evolution of deep water waves have never been made in this double limit. In the present work, we present the first experimental results with observations of the Peregrine soliton in a water wave tank.
950 citations
[...]
TL;DR: In most circumstances, the properties of rogue waves and their probability of occurrence appear to be consistent with second-order random-wave theory as mentioned in this paper, although it is unclear whether these represent measurement errors or statistical flukes, or are caused by physical mechanisms not covered by the model.
Abstract: Oceanic rogue waves are surface gravity waves whose wave heights are much larger than expected for the sea state. The common operational definition requires them to be at least twice as large as the significant wave height. In most circumstances, the properties of rogue waves and their probability of occurrence appear to be consistent with second-order random-wave theory. There are exceptions, although it is unclear whether these represent measurement errors or statistical flukes, or are caused by physical mechanisms not covered by the model. A clear deviation from second-order theory occurs in numerical simulations and wave-tank experiments, in which a higher frequency of occurrence of rogue waves is found in long-crested waves owing to a nonlinear instability.
777 citations
Book•
01 Mar 1987
TL;DR: In this article, the authors describe wave mechanics and how to choose wave theories and design waves, and how this wave is used to obtain forces on a fixed offshore structure, if the structure is allowed to move, various methods of obtaining the motions of the structure are given.
Abstract: The subject of hydrodynamics applied to offshore structures is vast. The topics covered in this book aim to help the reader understand basic principles while at the same time giving the designer enough information for particular designs. Thus, results are given with derivations, and applications are discussed with the aid of examples, with an overview of the advantages and limitations of the method involved. This makes the book suitable as a text for undergraduate and graduate students specializing in offshore and ocean engineering. In addition, the final results, including tables and illustrations may be referenced directly without going through detailed derivations. They can therefore be used by design and applications engineers involved in offshore structure design. This title also introduces various types of offshore structures with reference to actual installations in various parts of the world. It describes wave mechanics and how to choose wave theories and design waves. After a choice of design wave is made, the author describes how this wave is used to obtain forces on a fixed offshore structure. If the structure is allowed to move, various methods of obtaining the motions of the structure are given. The short- and long-term responses are derived and different methods are described. The use of model tests to verify these methods at each step is shown.
632 citations