scholarly journals Numerical Analysis of Wave Characteristic In the Freak Wave-- “New Year Wave” Formation

2021 ◽  
Vol 290 ◽  
pp. 02013
Author(s):  
Yu Xiang-jun ◽  
Li Qing-hong ◽  
Li Mao-lin
Keyword(s):  
Wave Spectrum ◽  
Random Wave ◽  
Small Range ◽  
Essential Factor ◽  
Transient Time ◽  
Freak Waves ◽  
Large Wave ◽  
Freak Wave ◽  
The North ◽  
The North Sea

Freak waves are both extremely large waves and highly transient time. Such a wave may lead to damage of ships to deaths. In this paper, to describe the connection between freak wave and wave essential factor, we use WAVEWATCH III model simulating “New Year Wave” in the North Sea to explore freak wave, with the importing of ECMWF re-analysis wind field. By this way, we successfully simulate the formation of freak wave in the random wave. Analysis shows large wave steepness and small directional spread angle are necessary conditions for freak waves to easily occur. By analyzing the wave spectrum, it is found that the wave energy is distributed in a small range, and the propagation direction is relatively concentrated.

The Thirty-Ninth Thomas Lowe Gray Lecture: Offshore Drilling, with Particular Reference to the North Sea and the ‘Sea Quest’

1966 ◽  
Vol 181 (1) ◽  
pp. 848-875 ◽  
Author(s):  
R. G. S. Avery
Keyword(s):  
North Sea ◽  
Essential Factor ◽  
Safety Equipment ◽  
Offshore Drilling ◽  
Advantages And Disadvantages ◽  
The North ◽  
Drilling Equipment ◽  
Sea Bed ◽  
Weight Problems ◽  
The North Sea

The origins of offshore drilling work and the development of structures used at sea are traced. Comparison of the various types illustrates the advantages and disadvantages of each. Tables show the numbers in operation, being built, and the apparent liability of each type to damage. Typical bore-hole structures are illustrated, the need for undersea well-heads explained and their development into a sea-bed completion is discussed. Much more research is necessary before this can be considered a practical proposition. The design of drilling barge equipment is compared with typical land rigs and the development of drilling equipment, including the sophisticated electric drive and turbo-drill, discussed. Rigs in various types of barge are compared. Fire precautions and other safety equipment are described. The problems associated with control by the driller lead to complications of motive power layout. The lecture describes in some detail the design of the semi-submersible drilling barge Sea Quest, illustrates the weight problems and their effect on floating stability and indicates the need for management decisions on the degree of resistance to damage. This is measured by the variable deck load of drilling equipment that can be held on board and the degree of weather deterioration that can be tolerated before disengaging the drill from the hole. The need for, and extent of, diving is discussed, with some comparison between diving vehicles. Weather too is an essential factor of work in the North Sea and both pre-surveys and day-to-day reporting are described.

Modeling freak waves from the North Sea

2005 ◽  
Vol 27 (1) ◽  
pp. 12-22 ◽  
Author(s):  
A. Slunyaev ◽  
E. Pelinovsky ◽  
C. Guedes Soares
Keyword(s):  
North Sea ◽  
Freak Waves ◽  
The North ◽  
The North Sea

Nonlinear and Dissipative Characteristics of a Combined Random-Cnoidal Wave Field

2017 ◽  
Author(s):  
James M. Kaihatu ◽  
John T. Goertz ◽  
Samira Ardani ◽  
Alex Sheremet
Keyword(s):  
Wave Spectrum ◽  
Leading Edge ◽  
Dissipation Function ◽  
Indian Ocean Tsunami ◽  
Random Wave ◽  
Cnoidal Wave ◽  
State University ◽  
Large Wave ◽  
Wave Flume ◽  
Wave Trains

Images of the 2004 Indian Ocean tsunami at landfall shows a leading edge marked by short waves (“fission” waves). These waves appear to be cnoidal in shape and of a temporal and spatial scale in line with the longest swell present in the region, and may interact with the longer waves in the background random wave spectrum. As part of a comprehensive series of experiments, the Large Wave Flume at Oregon State University (USA) was used to generate and measure the properties of cnoidal, random, and combined cnoidal-random wave trains. Both the nonlinear energy transfer characteristics (via bispectral analysis) and dissipation characteristics (via a proxy dissipation function) are studied for all generated wave conditions. It is generally determined that the characteristics of the cnoidal wave dominate the combined cnoidal-random wave signals if the energy of the cnoidal wave is at least equal to that of the random wave.

scholarly journals 3-D HOS simulations of extreme waves in open seas

2007 ◽  
Vol 7 (1) ◽  
pp. 109-122 ◽  
Author(s):  
G. Ducrozet ◽  
F. Bonnefoy ◽  
D. Le Touzé ◽  
P. Ferrant
Keyword(s):  
Wave Spectrum ◽  
Original Study ◽  
Test Cases ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Freak Waves ◽  
Freak Wave ◽  
Directional Spectrum ◽  
Long Time ◽  
Directional Wave

Abstract. In the present paper we propose a method for studying extreme-wave appearance based on the Higher-Order Spectral (HOS) technique proposed by West et al. (1987) and Dommermuth and Yue (1987). The enhanced HOS model we use is presented and validated on test cases. Investigations of freak-wave events appearing within long-time evolutions of 2-D and 3-D wavefields in open seas are then realized, and the results are discussed. Such events are obtained in our periodic-domain HOS model by using different kinds of configurations: either i) we impose an initial 3-D directional spectrum with the phases adjusted so as to form a focused forced event after a while, or ii) we let 2-D and 3-D wavefields defined by a directional wave spectrum evolve up to the natural appearance of freak waves. Finally, we investigate the influence of directionality on extreme wave events with an original study of the 3-D shape of the detected freak waves.

Occurrence of Freak Waves in near-coast regions of the North Sea and their potential relationship with objective weather types

2020 ◽  
Author(s):  
Jens Möller ◽  
Ina Teutsch ◽  
Ralf Weisse
Keyword(s):  
North Sea ◽  
German Bight ◽  
Climate Model ◽  
Rogue Waves ◽  
Freak Waves ◽  
Weather Types ◽  
The North ◽  
Ocean Atmosphere ◽  
The Future ◽  
The North Sea

<p>Rogue waves are a potential threat for both shipping and offshore structures like wind power stations or oil platforms. While individual Rogue waves are short-lived and almost unpredictable, there is a chance to predict the probability of the occurrence of freak waves in conjunction with different weather types. The German Ministry of Transport and digital Infrastructure has tasked its Network of Experts to investigate the possible evolutions of extreme threats for shipping and offshore wind energy plants in the German Bight, the south-eastern part of the North Sea near the German coast.</p><p>In this study, we present an analysis from the co-occurrence of freak waves with different weather types in the German Bight in the past (from observations). In addition, we investigate potential changes of the occurrence of freak waves in the future due to a changing climate and changing appearance of the relevant weather types (by use of a coupled Regional Ocean-Atmosphere Climate Model, MPI-OM).</p><p>The investigation indicates a connection between the probability of the occurrence of freak waves at different stations and certain weather types. Potentially, this relationship could be used for warning crews of ships or offshore constructions. In a coupled Regional Ocean-Atmosphere Climate Model (MPI-OM) under scenario RCP8.5 we detect an increase of just such weather types, which are correlated with high waves, for the future.</p>

Reconstruction and Analysis of Freak Waves Generated From Unidirectional Random Waves

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Yuxiang Ma ◽  
Changfu Yuan ◽  
Congfang Ai ◽  
Guohai Dong
Keyword(s):  
Time Series ◽  
Extreme Event ◽  
Wave Model ◽  
Rogue Waves ◽  
Random Wave ◽  
Random Waves ◽  
Long Distance ◽  
Freak Waves ◽  
Freak Wave ◽  
Wave Flume

Abstract The generation of two freak waves in a broadband and a narrowband random series registered in the experiments of Li, J. X., Li, P. F., and Liu, S. X. (2013, “Observations of Freak Waves in Random Wave Field in 2D Experimental Wave Flume,” China Ocean Eng., 27(5), pp. 659–670) is precisely reconstructed using a fully non-hydrostatic water wave model. The simulation results indicate that even when the background spectral bandwidths are different, the evolution processes of the two freak waves are similar. Both freak waves emerge quickly during the transition from normal states to extreme events. The freak waves can persist over a long distance, i.e., approximately 5 peak wavelengths. The reconstructed time series in both the backward and forward locations at which the freak waves were recorded reveal that the largest freak wave crests were not captured in the experiment. The freak waves gradually emerged from an intense wave group. The waves developed quickly during the transition from a normal state to an extreme event. Very deep troughs were also formed in the evolution process. The two freak waves were actually generated via different spectral bandwidth processes, but the generation mechanisms of the rogue waves were similar. By analyzing the time series of the freak wave groups, the formation of the freak waves is found to result from the combined effect of the dispersive focusing, the third-order resonant wave interactions, and the higher harmonics.

scholarly journals Coherence and predictability of extreme events in irregular waves

2012 ◽  
Vol 19 (2) ◽  
pp. 199-213 ◽  
Author(s):  
A. L. Latifah ◽  
E. van Groesen
Keyword(s):  
Nonlinear Effects ◽  
Exceptional Case ◽  
Irregular Waves ◽  
Time Signal ◽  
Freak Waves ◽  
Position Information ◽  
Large Wave ◽  
Freak Wave ◽  
First Case ◽  
Time Trace

Abstract. This paper concerns the description and the predictability of a freak event when at a certain position information in the form of a time signal is given. The prediction will use the phase information for an estimate of the position and time of the occurrence of a large wave, and to predict the measure of phase coherence at the estimated focussing position. The coherence and the spectrum will determine an estimate for the amplitude. After adjusting for second order nonlinear effects, together this then provides an estimate of the form of a possible freak wave in the time signal, which will be described by a pseudo-maximal signal. In the exceptional case of a fully coherent signal, it can be described well by a so-called maximal signal. We give four cases of freak waves for which we compare results of predictions with available measured (and simulated) results by nonlinear AB-equation (van Groesen and Andonowati, 2007; van Groesen et al., 2010). The first case deals with dispersive focussing, for which all phases are (designed to be) very coherent at position and time of focussing; this wave is nearly a maximal wave. The second case is the Draupner wave, for which the signal turns out to be recorded very close to its maximal wave height. It is less coherent but can be described in a good approximation as a pseudo-maximal wave. The last two cases are irregular waves which were measured at MARIN (Maritime Research Institute Netherlands); in a time trace of more than 1000 waves freak-like waves appeared "accidentally". Although the highest wave is less coherent than the other two cases, this maximal crest can still be approximated by a pseudo-maximal wave.

Use of Spaceborne Synthetic Aperture Radar for Offshore Wave Analysis

2004 ◽  
Author(s):  
Jose´ C. Nieto-Borge ◽  
Susanne Lehner ◽  
Tobias Schneiderhan ◽  
Johannes Schulz-Stellenfleth ◽  
Andreas Niedermeier
Keyword(s):  
Synthetic Aperture Radar ◽  
North Sea ◽  
Wave Spectrum ◽  
Surface Wind ◽  
Global Scale ◽  
Synthetic Aperture ◽  
Sar Images ◽  
The North ◽  
The North Sea ◽  
Aperture Radar

Spaceborne Synthetic Aperture Radar (SAR) is able to provide sea state information on a global scale by means of the directional wave spectrum. Recent developed algorithms have been developed to obtain additional information in the spatial domain rather than the spectral domain. These methods permit to detect of individual wave heights, wave groupiness in open sea areas, as well as surface wind fields. This work shows the capabilities of spaceborne SAR to extract offshore information about individual waves and wave grouping for areas of about 100 × 100 square kilometers. The methods are applied to ERS-2 SAR images of the North Sea over areas close to the location of some oil platforms. Results obtained in the vicinity of the Ekofisk platform are shown. In addition, ERS-2 SAR images taken on January 1, 1995 over the Draupner platform in the North Sea are analyzed. These SAR images were taken at the approximate time when the wave record known as “new year wave” was measured.

A CFD Application of NewWave Theory to Wave-in-Deck Simulation

2016 ◽  
Vol 13 (02) ◽  
pp. 1640014 ◽  
Author(s):  
Yan Ling Wu ◽  
Graham Stewart ◽  
Yu Chen ◽  
Johan Gullman-Strand ◽  
Xin Lv ◽  
...  
Keyword(s):  
Open Source Software ◽  
Wave Theory ◽  
Numerical Approach ◽  
Air Gap ◽  
Sea Surface ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Large Wave ◽  
The North ◽  
The North Sea

For existing offshore fixed platforms it is often the case that the air gap between the deck and the sea surface is not adequate and the extreme waves will encroach on the deck resulting in large wave-in-deck loads. Factors that result in inadequate air gap are seabed subsidence, sea-level increasing due to climate change and more onerous predictions of extreme crest heights. In this paper, a numerical approach based on NewWave theory [Tromans et al. (1991), Proc. 1st Int. Offshore and Polar Engineering Conf., Vol. 3, Edinburgh, UK, pp. 64–71] has been developed to represent the extreme wave conditions and implemented into the framework of an open source software, OpenFOAM, to predict the wave-in-deck loading. The results have been compared with published FLOW-3D simulations using Stoke’s 5th order wave theory for a simple box representing the Ekofisk platform deck in the Norwegian sector of the North Sea [Iwanowski et al. (2002), Proc. 21st Int. Conf. Offshore Mechanics and Artic Engineering, June 23–28, 2002, Oslo, Norway].

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