Imperial College London
Alternate

Emeritus ProfessorChrisSwan

Faculty of Engineering, Department of Civil and Environmental Engineering

Emeritus Professor of Hydrodynamics
 
 
 
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Contact

 

+44 (0)20 7594 5999c.swan

 
 
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Assistant

 

Miss Rebecca Naessens +44 (0)20 7594 5990

 
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Location

 

329Skempton BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Gibson:2007:10.1098/rspa.2006.1729,
author = {Gibson, RS and Swan, C},
doi = {10.1098/rspa.2006.1729},
journal = {P R SOC A},
pages = {21--48},
title = {The evolution of large ocean waves: the role of local and rapid spectral changes},
url = {http://dx.doi.org/10.1098/rspa.2006.1729},
volume = {463},
year = {2007}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This paper concerns the formation of large-focused or near-focused waves in both unidirectional and directional sea-states. When the crests of wave components of varying frequency superimpose at one point in space and time, a large, transient, focused wave can occur. These events are believed to be representative of the largest waves arising in a random sea and, as such, are of importance to the design of marine structures. The details of how such waves form also offer an explanation for the formation of the so-called freak or rogue waves in deep water. The physical mechanisms that govern the evolution of focused waves have been investigated by applying both the fully nonlinear wave model of Bateman et al. (Bateman et al. 2001 J. Comput. Phys. 174, 277 305) and the Zakharov's evolution equation (Zakharov 1968 J. Appl. Mech. Tech. Phys. 9, 190 194). Aspects of these two wave models are complementary, and their combined use allows the full nonlinearity to be considered and, at the same time, provides insights into the dominant physical processes.In unidirectional seas, it has been shown that the local evolution of thewave spectrumleads to larger maximum crest elevations. In contrast, in directional seas, the maximum crest elevation iswellpredictedby a second-order theory based on the underlying spectrum, but the shape of the largest wave is not. The differences between the evolution of large waves in unidirectional and directional sea-states have been investigated by analysing the results of Bateman et al. (2001) using a number of spectral analysis techniques. It has been shown that during the formation of a focused wave event, there are significant and rapid changes to the underlying wave spectrum. These changes alter both the amplitude of the wave components and their dispersive properties. Importantly, in unidirectional sea-states, the bandwidth of the spectrum typically increases; whereas, in directional sea-states it decreases.The changes to thewave spectra have
AU  - Gibson,RS
AU  - Swan,C
DO  - 10.1098/rspa.2006.1729
EP  - 48
PY  - 2007///
SN  - 1364-5021
SP  - 21
TI  - The evolution of large ocean waves: the role of local and rapid spectral changes
T2  - P R SOC A
UR  - http://dx.doi.org/10.1098/rspa.2006.1729
VL  - 463
ER  -
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