A Comparative Review on the Functional Forms of Directional Wave Spectrum

Abstract

Standard functional forms of directional wave spectrum are presented and compared. Frequency spectra of the JONSWAP, Wallops, and TMA are presented as the functions of significant wave height and spectral peak period. In combination with these frequency spectra, directional spreading functions of cos2s(θ/2), cos2l' θ, exp[k cos θ], sech2βθ, the wrapped normal, and the Mitsuyasu types are compared for their functional shapes, angular standard deviations, and half-peak spreading angles. Empirical relations between the spreading parameters of these directional functions are presented.