in the breaking region were presented. A flow field obtained by averaging 10 instantaneous flow fields clearly shows the evolution of a shear layer between the nearly stagnant fluid in the breaking region and the fast-moving underlying flow. From this preliminary data, it appears that the flow at the free surface near the crest is directed downstream.
This work was supported by the Office of Naval Research under contract N00014–90-J-1977 and the David Taylor Model Basin (DTMB). The authors acknowledge a number of helpful discussions with D.Rockwell and J.Katz on PIV techniques. Haibing Qiao assisted in the data acquisition of the breaker region PIV experiments, construction of the PIV equipment, and in writing some of the PIV analysis software. John Hamilton of DTMB engineered and built a timing device that was used in the PIV measurements. Alexandra Wenz developed most of the high-speed films used during these experiments. Arno Miessner and Sebastian Muncher helped to analyze some of the early high-speed movie films. Sven Eisen helped to construct some of the tank apparatus. Bruce Webster of DTMB is gratefully acknowledged for his patience in allowing a flexible work schedule for Mr. Coakley.
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