Generation of Controlled Irregular Wave Crest Statistics in a Numerical Wavetank Using HOS-NWT Solver

• Published in: Volume 5B: Ocean Engineering; Honoring Symposium for Professor Günther F. Clauss on Hydrodynamics and Ocean Engineering
• Main Authors: Canard, Maxime, Ducrozet, Guillaume, Bouscasse, Benjamin
• Other Authors: Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), ANR-16-IDEX-0007,NExT (I-SITE),NExT (I-SITE)(2016)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SPI]Engineering Sciences [physics]; Arctic
• Online Access: https://hal.science/hal-04490950; https://doi.org/10.1115/OMAE2022-79880

International audience Abstract In order to assess the reliability of offshore structures facing extreme environmental conditions, sea keeping tests are performed at model scale in experimental or numerical wave tanks. The scope of the present paper is limited to the generation of wave condition for such tests. The vast majority of industrial practices follow a stochastic approach. For each design sea state, several realizations of long irregular wave sequences are generated. The qualification of the waves mainly relies on the analysis of the mean spectrum and the ensemble crest height distribution at the structure (target) location (Xt). However, the wave propagation from the wavemaker to Xt is affected by nonlinear mechanisms and dissipation phenomena which lead to uncontrolled variations of the quantities of interest. To face those issues, the most advanced wave generation procedures usually focus on the quality of the wave spectrum at Xt, iterating on the wave maker motions. Nevertheless, depending on Xt, the crest height statistics can significantly differ. For instance with steep and narrow-banded unidirectional sea states, the distributions obtained at target locations far from the wave maker (Xt > 20λp, λp being the peak wavelength) enlighten a significant number of extreme events that are likely to strongly affect the response of the tested structure. On those grounds, the present study proposes a procedure that offers the possibility to reproduce those extreme statistics at locations closer to the wavemaker. The framework is limited to non breaking unidirectional waves. The procedure is numerically tested with the open-source nonlinear potential wave solver HOS-NWT. The study opens the way to an accurate control of the wave statistics at any location in a wave tank environment.