First order stochastic Lagrange models for front-back asymmetric ocean waves

Georg Lindgren and Sofia Åberg

Abstract:: The Gaussian linear wave model, which has been successfully used in ocean engineering for more than half a century, is well understood, and there exists both exact theory and efficient
numerical algorithms for calculation of the statistical distribution of wave characteristics. It is well suited for moderate seastates and deep water conditions. One drawback, however, is its lack of realism under extreme or shallow water conditions, in particular its symmetry. It produces waves which are stochastically symmetric, both in the vertical and in the horizontal direction. From that point of view, the Lagrangian wave model, which describes the horizontal and vertical movements of individual water particles, is more realistic. Its stochastic properties are much less known, and have not been studied until quite recently. This paper presents a version of the first order stochastic Lagrange model that is able to generate irregular waves with both crest-trough and
front-back asymmetry.

Key words:: Gaussian process, occupation density, significant wave height, wave height