Measured Internal Kinematics for Shoaling Waves with Theoretical Comparisons

Abstract

Measurements of both the velocities and Eulerian accelerations have been made in the crests of waves at their breaking point. Measurement close to the wave surface (5 mm) has been made possible by the use of a very rapid response laser Doppler anemometer. The results have enabled critical comparisons to be made with mathematical wave models used in offshore design. At low levels within the waves, there is agreement between the theories, and the predictions are conservative. However, in the high crest most models seriously underpredict the kinematics. Validation of the models based on previously available results is shown to be limited in scope. This experiment was conducted in a wave flume using monochromatic waves shoaling on a flat bed and on slopes of 1:50, 1:30, and 1:15. Breaking wave heights were about 0.1 m, surface tension effects were negligible, and breaking occurred over a range of nondimensional depth