The Dispersion Relation for Wind Waves in Decay Area

Abstract

Random waves are generated by wind in the first half of a wind-wave flume. The latter half of the flume is kept free from wind to measure the wave characteristics unaffected by the wind and wind-generated current. The waves in the latter (decay) area are measured with a linear array of wave gauges, and their phase velocities and coherences are determined by a usual technique of the cross-spectral analysis. The measured results are compared with the third-order approximation to the theory of two-dimensional random waves, which we have developed recently (Masuda et al. 1977). Agreement between the theory and the experiment is satisfactory, and observed characteristics of the phase velocity and coherence of the spectral components can be attributed to the effects of the nonlinearity and angular dispersion of the random waves.