High-Resolution Planar Two-Component PTV Measurements in a Breaking Wave

Ocean waves and the associated wave forces are of vital importance for marine applications, with offshore wind turbines as one example. Since the wave forces are governed by the wave kinematics, detailed studies of wave kinematics are highly valuable. In this study, wave kinematics of a breaking laboratory wave is investigated using dynamic masking and Particle Tracking Velocimetry (PTV).

First, dynamic masking is used to remove the bubble-droplet layer above the free surface. Second, PTV is used to resolve the kinematics with high spatial resolution throughout the wave motion from the laboratory bed to the water surface. Instantaneous velocity fields are obtained at a sample rate of 96Hz, and this provides sufficient temporal resolution for spectrum and acceleration investigations.

The results indicate that, compared to Particle Image Velocimetry (PIV), the current methodology provides a better understanding for the dynamics of ocean waves, thus leading to more accurate predictions of wave forces.