Non-Gaussian extreme waves in the Central North Sea
- Danish Hydraulic Inst., Hoersholm (Denmark)
- LICengineering AS, Hellerup (Denmark)
- Maersk Olie og Gas AS, Esbjerg (Denmark)
The area of the Central North Sea is notorious for the occurrence of very high waves in certain wave trains. The short term distribution of these wave trains includes waves which are far steeper than predicted by the Rayleigh distribution. Such waves are often termed extreme waves or freak waves. An analysis of the extreme statistical properties of these waves has been made. The analysis is based on more than 12 years of wave records from the Maersk Olie og Gas AS operated Gorm Field which is located in the Danish sector of the Central North Sea. From the wave recordings more than 400 freak wave candidates were found. The ratio between the expected extreme crest height and the significant wave height (20-minute value) has been found to be about 1.8, and the expected ratio between extreme crest height and extreme wave height has been found to be 0.69. These values are clearly outside the range of Gaussian waves. The latter value, which is higher than the maximum value for steep non-linear long-crested waves, indicates that the freak waves are not of permanent form, and that they are probably of short-crested nature. The extreme statistical distribution is found to be very well represented by a Weibull distribution with an upper bound, where the upper bound is the value for a depth limited breaking wave. Based on the measured data a procedure for determining the freak wave crest height with a given return period is proposed. A sensitivity analysis of the extreme value of the crest height is also made.
- OSTI ID:
- 449647
- Report Number(s):
- CONF-9606279-; ISBN 0-7918-1490-4; TRN: IM9714%%204
- Resource Relation:
- Conference: 14. international conference on offshore mechanics arctic engineering (OMAE), Florence (Italy), 16-20 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings of the 15. international conference on offshore mechanics and arctic engineering -- OMAE 1996. Volume 1, Part A: Offshore technology; Chakrabarti, S.K. [ed.] [Chicago Bridge and Iron Technical Services Co., Plainfield, IL (United States)]; Pontes, M.T. [ed.] [Inst. Nacional de Engenharia e Tecnologia Industrial, Lisbon (Portugal)]; Maeda, Hisaaki [ed.] [Univ. of Tokyo (Japan)]; Falzarano, J. [ed.] [Univ. of New Orleans, LA (United States)]; Schofield, P. [ed.] [W.S. Atkins, Surrey (United Kingdom)]; Morrison, D. [ed.] [Shell E and P Technology Co., Houston, TX (United States)]; PB: 530 p.
- Country of Publication:
- United States
- Language:
- English
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