EGU22-11154
https://doi.org/10.5194/egusphere-egu22-11154
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Control of crest heigth statistics at a target position in a wave tank environement

Maxime Canard1, Guillaume Ducrozet2, and Benjamin Bouscasse3
Maxime Canard et al.
  • 1Ecole Centrale De Nantes, LHEEA, France (maxime.canard@ec-nantes.fr)
  • 2Ecole Centrale De Nantes, LHEEA, France (guillaume.ducrozet@ec-nantes.fr)
  • 3Ecole Centrale De Nantes, LHEEA, France (benjamin.bouscasse@ec-nantes.fr)

The present study deals with the generation and the propagation of unidirectional irregular waves in experimental or numerical wave tanks. It introduces, tests and validates a new wave generation procedure, allowing for the accurate control of a generated sea state at any position of the domain.

A sea state represents the wave conditions observed at sea. It is defined with a wave spectrum and a certain duration, associated to the probability of occurrence of the extreme events. A sea state can be reproduced at model scale in wave tanks, usually for wave structure interaction tests with a typical duration of 3hours at full scale.

To generate a sea state, the usual procedures rely on a stochastic approach. Long-duration free surface elevation time-series (realizations) are generated by the wave maker. They are built in the Fourier space using the linear dispersive waves theory. The amplitudes are set using the wave spectrum of interest, and the phases are random. The quality of the generated wave field is then assessed at a target position Xt (usually the position of a tested marine structure). The qualification of the sea state at Xt mainly rely on the mean wave spectrum (over all the realizations) and the ensemble crest heigth distribution (considering all the realizations).

However, nonlinear phenomena occur from the wave maker to the target position. They affect the shape of the spectrum and deviate the crest distributions from its references. The most advanced state-of-the-art wave generation procedures iterate on the wave maker motion to correct the spectrum at Xt. However, recent studies [1] show that using such methods, the crest statistics can strongly vary with Xt.

On those grounds, our new procedure complete the state-of-the-art methodologies. It allows for the control of the spectrum together with the crest distributon at any target position. The method is numerically tested and validated with the nonlinear wave propagation solver HOS-NWT [2]. And some preliminary experimental results are presented.

 

[1] Canard, M., Ducrozet, G., and Bouscasse, B., 2022 (accept-edfor publication). Varying ocean wave statistics emerg-ing from a single energy spectrum in an experimental wavetank. Ocean Engineering.

[2] Ducrozet, G., Bonnefoy, F., Le Touzé, D., & Ferrant, P. (2012). A modified high-order spectral method for wavemaker modeling in a numerical wave tank. European Journal of Mechanics-B/Fluids, 34, 19-34.

How to cite: Canard, M., Ducrozet, G., and Bouscasse, B.: Control of crest heigth statistics at a target position in a wave tank environement, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11154, https://doi.org/10.5194/egusphere-egu22-11154, 2022.