Experimental Investigation Of The Characteristics Of Wind-wave Under Steady Wind And Unsteady Wind

Oceans and lakes are important in China's reserve of resources and social and economic development.Therefore,it is very important to study the characteristics of wind and waves for ocean engineering construction,maritime activities and water resources utilization.The dissertation reviews the development of research,carrying out the experimental study of the characteristics of wind-wave under steady wind and unsteady wind,and the law of the growth and propagation of wind wave,to provide basic data and observation basis for mathematical model research and engineering.(1)The anemometer was used to measure wind speed data and obtained the distribution of wind speed,under steady wind,in the near-surface area is satisfied with logarithmic distribution;the friction factor CD will decrease with the increase of the backwater factor Vz=100cm2/2gh and then keep the range fluctuation;Using wave height to collect wind wave surface data,through statistical analysis method,obtain the characteristic values of wind waves under steady wind and unsteady wind,and master the changing rules of wind waves changing with wind speed and fetch.And then combining the two results,obtain the relationship between the elements wind wave under steady wind and unsteady wind,the wave height and wavelength increase with the wind speed and wind fetch,when the fetch more than 10 meters,the wave height growing under the large wind speed will be slow for the breaking of the wave.When the fetch is less than 10 meters,the phenomenon of water reducing will happen.When the fetch is more than 10meters,there will be a backwater phenomenon.(2)Using spectral analysis method,reveal the change tendency of wind wave spectrum and internal energy structure,the wave main frequency is shifted to the low frequency with the wind speed and fetch,specially under unsteady wind effect,the main frequency of the wind wave will shift to the low frequency direction after crossing the wavelet jitter phase,the band width is narrowed,and the multi-peak is formed to the unimodal trend.(3)Analyze the statistical eigenvalues and then the variation rule of wind wave under unsteady wind,growth and attenuation is obtained.When the wind waves grow,the main frequency is dispersed and then concentrated toward the low frequencies,meanwhile,the spectral peak is changed by the change of peaks,and the wave steepness has obvious growth characteristics.However,when the wind waves are weak,the wave steepness in the small fetch will be obvious reduction.