Session: 02-04-02 Probabilistic and Spectral Wave Modelling (Co-hosted with the Ian Young Honoring Symposium)

Paper Number: 102095

102095 - DIRECTIONAL WAVE SPECTRA BY MEANS OF A FULLY NONLINEAR WAVE MODEL 

The directional wave spectrum describes characteristics of ocean waves in the wavenumber or frequency domain; it is fundamental for most wind wave research and is widely used in ocean engineering and naval architecture. Although the concept is more than half a century old, improvements in estimating directional wave spectra are still of significant interest.

This study aims to improve the accuracy of traditional methods for obtaining the directional spectrum gleaned from point measurements by contrasting them with a method that uses the 2D Fourier transform (2DFT) of the water surface. This will be done by using numerical simulations and measurements from a wave basin.

Simulations of the free surface for different sea states will be made using a 3D fully nonlinear phase resolving model. The directional wave spectra across frequency will be estimated using the Maximum Likelihood Method (MLM), Maximum Entropy Method (MEM) and Wavelet Directional Method (WDM) and intercompared using the estimations from the 2DFT of the water surface as a reference to establish the performance of the methods.

The results will then be validated with data measured with stereo imaging techniques in a wave basin. Stereo-imaging measurements allow the discretization of the free surface into a regular 2D grid that can be used for Fourier analysis. The directional distribution of the transfer functions based on MLM, MEM and WDM will be estimated and compared with the 2DFT directional wave spectra.

Furthermore, an estimation of wave-breaking statistics, i.e. breaking probability and severity, and its directional distribution across the frequency spectrum will be explored. 

Presenting Author: Omar Zain Torres Rios University of Melbourne

Presenting Author Biography: I studied for my bachelor's degree in Oceanology at the University of Baja California (UABC) and a Master's in Physical Oceanography at CICESE (Mexico).
My main research topic was to study the influence of waves on the relative dispersion of passive tracers under extreme wind conditions using numerical simulation.
I am currently studying for a PhD in Ocean engineering at the University of Melbourne (Australia), focused on directional spectra and the distribution of wave-breaking dissipation across the frequency spectrum.

Authors:

Omar Zain Torres Rios University of Melbourne
Alexander Babanin University of Melbourne
Ian Young University of Melbourne
Sannasi Annamalaisamy Sannasiraj Indian Institute Of Technology