Seminars

High resolution infrared (IR)  imagery of breaking waves in a wave-tank free of wind shear or current reveals the production of a “streaky,” quasi-periodic thermal pattern produced during the breaking process*. The streaks, or elongated patterns of warm and cold fluid, are found to form only when surface turbulence is present before wave breaking occurs. This suggests that wave-turbulence interaction is one mechanism that can lead to streak formation in breaking wave systems. More specifically, the streaky structures observed in these experiments may be caused by an intense, rapid tilting and stretching of pre-existing vertical vorticity by the Stokes drift generated at or near the breaking wave crests, thereby generating a coherent system of counter-rotating vortices. We attempt to relate our observations to the recent theory of Teixeira and Belcher [J. Fluid Mech. 458, 229–267 (2002)]. Some properties of the streaks, such as the dependence of their lifetimes and spanwise scale on wave amplitude, are also presented.