Abstract
In the sea, which is affected by strong winds that cover the water surface with wind wave breakers, a strong turbulent boundary layer is generated immediately below the sea surface. To clarify the turbulent structure of the sea-surface boundary layer, it is necessary to measure correctly water particle velocity fields in that layer. However, there are great difficulties in the measurement because the sea surface is covered by developed wind waves accompanied by air bubbles, air flow separation, and large water surface displacements. In this study, a high-resolution PIV system, which can analyze high-speed and intensively fluctuating water particle velocities that are affected by breaking waves, is developed to obtain correctly the data of the water particle velocity fields immediately below the water surface. Further, investigation and modeling of the turbulent structure of the sea-surface boundary layer are performed based on the velocity data obtained by a water tank experiment using the high-resolution PIV system.
