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1 . AGENCY USE ONLY (Leave blank) 



2. REPORT DATE 



September 1998 



3. REPORT TYPE AND DATES COVERED 



Final report 



4. TITLE AND SUBTITLE 



Directional Irregular Wave Kinematics 



6. AUTHOR(S} 



Christopher H. Barker, Rodney J. Sobey 



5. FUNDING NUMBERS 



7. PERFORMING ORGANIZATION NAME(S) AND AODRESS(ES) 



University of California at Berkeley 

 Berkeley, CA 94720 



8. PERFORMING ORGANIZATION 

 REPORT NUMBER 



Technical Report CHL-98-24 



9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 



U.S. Army Corps of Engineers, Washington, DC 203 14- 1000 



U.S. Army Engineer Waterways Experiment Station 



3909 Halls Ferry Road, Vicksburg, MS 39180-6199 



10. SPONSORING/MONITORING 

 AGENCY REPORT NUMBER 



11. SUPPLEMENTARY NOTES 



Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. 



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Approved for public release; distribution is unlimited. 



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ABSTRACT (Maximum 200 words) 



Coastal and ocean processes are heavily influenced by the kinematics of waves. In order to understand these processes, 

 researchers place a variety of instruments in the sea in an attempt to measure the waves. These instruments all measure a 

 small set of physical quantities at a small number of locations. The balance of the kinematics must be predicted through 

 analysis of the measured records. Most of the currently used methods of analysis rely on the superposition of linear waves to 

 recreate complex seas. These methods are compromised by linearizing ^iproximations to the free surface boundary 

 conditions. Fidelity in the interpretation of wave measurements is enhanced by insisting that the analysis satisfies the fiill 

 nonlinear free surface boundary conditions. 



The Local Fourier method for irregular wave kinematics (LFI) is introduced and expanded to include the interpretation of 

 records from arrays of instruments. It is a local method, in that a separate solution is sought that fits the measured record(s) in 

 a small local window in time, rather than attentpting to find a single solution for a large segment of the record. Each window 

 solution satisfies the fiill set of governing equations for gravity waves, including the nonlinear free surface boundary 

 conditions. The solution in each window is a potential fimction whose form is based upon a Stokes style expansion for 

 intersecting waves. The parameters of the potential fimction are found by a nonlinear optimization that seeks the solution that 

 matches the measured record and satisfies the fiill free surface boundary conditions. 



(Continued) 



14. 



SUBJECT TERMS 



Crest kiiKmatics 

 Local fourier method 

 Nonlinear waves 

 Wave gauges 



Wave kinematics 

 Wave measurements 

 Waves 



15. NUMBER OF PAGES 



183 



16. PRICE CODE 



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UNCLASSIFIED 



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