Computation of sea-wave direction of propagation of random waves

In the last 20 years, the application of the random wave theory in maritime engineering has been given the utmost importance, especially for evaluating design wave conditions, loads on structures, and sand littoral drift. The aim of the paper is to present a general expression for the evaluation of the local energy flux vector of random waves. This expression can be used for computing a representative direction of propagation of the wave spectrum in the presence of any scattering source. The effectiveness of the presented expression is shown by a numerical experiment. Moreover the expression is compared with the relationship that is normally used in field observations to represent the mean wave direction of a two-dimensional spectrum. The results of the comparison, carried out with a measured directional wave spectrum, are discussed