Laboratory observations of the kinematics in the aerated region of breaking waves

Abstract An experimental technique has been developed to visualize the flow in the aerated upper part of breaking waves. This technique, in which ultraviolet light and fluorescent particles are used, reveals sequences of jet-splash motions in that upper part of breaking waves during the initial stages of breaking. These motions are found to be qualitatively similar for two different types of breakers. The jet motion consists of particles moving down along the forward face of the wave; subsequently a splash motion is formed by the impact of the jet and its penetration through the free surface. Both motions are found to be reproducible coherent structures.