PREFACE 



This report presents an investigation of the potential value of a wind-wave 

 research facility for coastal engineering studies. The use of wind to generate 

 waves in the laboratory is frequently suggested by coastal engineers. The 

 report reviews earlier studies of wave generation, the flow of air in wind tun- 

 nels, and early laboratory experiments with wind-wave research facilities to aid 

 engineers in deciding if facilities of this type are useful for solving specific 

 problems. Ihe work was carried out under the wave mechanics program of the U.S. 

 Army Coastal Engineering Research Center (CERC) . 



The report was' prepared by Dr. D. Lee Harris, Chief, Oceanography Branch, 

 under the general supervision of R.P. Savage, Chief, Research Division, CERC. 



Dr. Harris has been interested in the use of wind-wave research facilities 

 for air-sea interaction studies for many years, and expresses his appreciation 

 to the many scientists who have contributed to this investigation. The oppor- 

 tunity of observing many combination wind tunnels-wave channels in action and 

 discussing their merits and shortcomings with scientists responsible for their 

 design and operation has been essential in performing this evaluation. An initial 

 visit to the laboratory at the National Bureau of Standards to observe experiments 

 by Dr. Keulegan was very informative, and was followed by later visits to this lab- 

 oratory after his retirement. Valuable discussions and demonstrations were con- 

 ducted with Professors Per Bruun and Frans Gerritsen, during construction and 

 operation of the combination wind tunnel-wave channel at the University of Florida; 

 and with Professor Omar Shemdin after modification of this facility in the late 

 1960's. Professor E.Y. Hsu, Stanford University, was most instructive in pointing 

 out the necessity of thickening the atmospheric boundary layer at the air-sea 

 interface to obtain the realistic wind profiles needed for activation of the Miles 

 inviscid wave-generating mechanism. Visits to other laboratories with working 

 wind-wave flumes in the United States, Japan, and Western Europe since 1965 have 

 provided additional perspective for the problems. Discussions with Professor James 

 Bole (during the summer he spent at CERC in 1972 and later) were extremely useful 

 in sorting out impressions gained in earlier laboratory visits and in reviewing 

 reports of scores of experiments involving the interaction of the air and the sea 

 in both laboratory and field. The author acknowledges his indebtedness to all these 

 individuals and to many others with experience in the laboratory study of wave gen- 

 eration who have shared their insights, and takes full responsibility for any mis- 

 understandings which may have resulted from these discussions. 



Comments on this publication are invited. 



Approved for publication in accordance with Public Law 166, 79th Congress, 

 approved 31 July 1945, as supplemented by Public Law 172, 88th Congress, approved 

 7 November 1963. 



P</^....\ 



?JOHN H. COUSINS 

 Colonel, Corps of Engineers 

 Commander and Director 



