Decomposition of incident and reflected surface waves using an Ultrasonic Velocity Profiler

In this article a novel method for estimating incident and reflected waves in wave flumes is presented. Instead of using water surface measurements obtained with a series of wave gages, we used water velocity measurements inside the water column obtained with an Ultrasonic Velocity Profiler to decompose the wave field. The technique allows for the identification of the incident and reflected first harmonic waves and the incident and reflected free and bound second harmonic waves. Only velocity measurements over a small fraction of the first harmonic wavelength are necessary to obtain reliable results, making the method suitable for studies where the water depth is not constant. Wave measurements obtained in a wave flume using four wave gages and three levels of wave reflection are used to evaluate the new method with excellent results. Finally, since no calibration of the velocity profiler is necessary, it is foreseen that the method could be implemented in a stand-alone instrument that would give the user the wave field decomposition without the need of a case by case set-up and calibration.

► Water velocity measurements are used to decompose incident and reflected waves.
► The method identifies free and bound second harmonic waves.
► Comparison with wave gage measurements gives excellent results.
► Three levels of beach reflection are studied.