d. Ramamonjiarisoa's E^cperiments . Ramamonjiarisoa (1973) presented 

 a comparison of wave spectra from field and laboratory studies which 

 showed that the spectra generated in laboratory wind-wave flumes are more 

 narrow than those obtained in the field and tkat, in nature, unlimited 

 fetches lead to broader spectra than limited fetch.es . This increasing 

 spectrum width with increasing fetch length is believed to result from 

 the greater variance of wind conditions over long fetches, and a greater 

 variance in the specific mechanisms responsible for wave generation when 

 long fetches are involved. 



2. Summary . 



A small sample of laboratory studies of the interaction between wind 

 and water is sufficient to show that these studies have provided con- 

 siderable new insight for the hydrodynamic processes involved. The phe- 

 nomena of concern are extremely complex. Some essential aspects of the 

 phenomena have been neglected in every experiment described in the lit- 

 erature. It appears that the technology necessary for quantitative 

 modeling of the processes by which momentum is passed from air to sea 

 has not yet been developed. It appears unlikely that a technology for 

 modeling the complete process can be developed in the foreseeable future. 



VI. SUMMARY AND CONCLUSIONS 

 1. Summary . 



The mechanically generated monochromatic waves, generally used in 

 laboratory studies of coastal engineering problems, are more regular in 

 height and period than the wind-generated waves observed in coastal 

 regions. The possibility of laboratory generation of waves which bear 

 a closer resemblance to prototype waves by combining a wind tunnel with 

 a wave flume, has a natural appeal to many research engineers. Moreover, 

 the existence of a combination wind tunnel-wave channel in engineering 

 laboratories would inspire much useful research related to the air-water 

 interaction processes of greatest concern to coastal engineers. 



A review of the extensive literature related to laboratory studies of 

 wind-wave generation shows that much qualitative understanding about wind- 

 wave generation has been obtained from laboratory studies, that much more 

 remains to be learned, and that every past experiment could be improved 

 in the light of knowledge available today. Thus, a combination wind 

 tunnel-wave channel could be a great aid to fundamental research in air-sea 

 interaction processes. 



The review of the literature dealing with the physical aspects of wave 

 generation shows that many complex microscale processes are involved. 

 Modeling these processes in the laboratory involves a great deal more than 

 blowing a known quantity of air across the water surface. Comparisons of 

 wave growth with increasing fetch and comparisons of the spectra of wind- 

 generated waves obtained under both laboratory and field conditions gives 

 little support to the notion that waves generated by wind in the laboratory 

 will be more suitable for engineering studies than mechanically generated 

 waves . 



37 



