Spatially evolving regular water wave under the action of steady wind forcing

Abstract

Detailed investigation of spatial evolution of mechanically generated regular water waves in a wind-wave tank under the action of steady wind is carried out. Deterministic waves are excited by a wavemaker driven at a range of frequencies and wavemaker displacement amplitudes. Prolonged measurements of the temporal variation of the instantaneous surface elevation carried out at multiple locations along the test section at numerous airflow rates enable obtaining reliable statistical parameters characterizing the wave-field evolution. Particular attention is given to the development along the tank of the wave frequency spectra as a result of wind input and interaction of the deterministic mechanical and the random wind waves. The interrelation between the regular and the random parts of the resulting wave field is studied in detail using auto- A nd cross-covariance analysis. Spatial coherence of the wave field is evaluated as a function of frequency for different wavemaker operation parameters and wind. The accumulated results allow us to draw conclusions regarding the effect of the high-frequency waves at short fetches evolving under the action of wind-wave field at more remote locations.