Field verification of linear and nonlinear hybrid wave models for offshore tower response prediction
- Hudson Engineering, Houston, TX (United States). Offshore Structural Div.
- Rice Univ., Houston, TX (United States). Dept. of Civil Engineering
Accuracy of the prediction of the dynamic response of deepwater fixed offshore platforms to irregular sea waves depends very much on the theory used to determine water kinematics from the mudline to the free surface. A common industry practice consists of using linear wave theory, which assumes infinitesimal wave steepness, in conjunction with empirical wave stretching techniques to provide a more realistic representation of near surface kinematics. The current velocity field is then added to the wave-induced fluid velocity field and the wave-and-current forces acting on the structure are computed via Morrison`s equation. The first objective of this study is to compare the predicted responses of Cognac, a deepwater fixed platform, obtained from various empirically stretched linear wave models with the response of Cognac predicted based on the Hybrid Wave Model. The latter is a recently developed higher-order, and therefore more accurate, wave model which satisfies, up to the second-order in wave steepness, the local mass conservation and the free surface boundary conditions up to the free surface. The second objective of this study consists of comparing the various analytical response predictions with the measured response of the Cognac platform. Availability of a set of oceanographic and structural vibration data for Cognac provides a unique opportunity to evaluate the prediction ability of traditional analytical models used in designing such structures. The results of this study indicate that (1) the use of the Hybrid Wave Model provides a predicted platform response which is in closer agreement with the measured response than the predictions based on the various stretched linear wave models; and (2) the Wheeler stretching technique produces platform response results which are more accurate than those obtained by using the other stretching schemes considered here.
- OSTI ID:
- 449645
- Report Number(s):
- CONF-9606279-; ISBN 0-7918-1490-4; TRN: IM9714%%202
- 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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