A Spectral Response Surface Method for Calculating Crest Elevation Statistics

Abstract

The statistics of wave crest elevation in a random, directionally spread sea are calculated using a novel approach. The non-linearity of steep waves is modelled to second order using Sharma and Dean kinematics and a spectral response surface method is used to deduce the crest elevation corresponding to a given probability of exceedance. The spectral response surface method works in the probability domain, making it several times faster than conventional time domain simulation of random waves. However, the results from the two methods show good agreement. As expected, non-linearity makes extreme crests higher than the corresponding linear ones.