Video measurements of fluid velocities and water levels in breaking waves

Abstract

The cost-effective measurement of the velocity flow fields in breaking water waves, using particle and correlation image velocimetry, is described. The fluid velocities are estimated by tracking the motion of neutrally buoyant particles and aeration structures. Results of the phase-ensemble-averaged velocity flow fields, time-averaged horizontal velocities and turbulence results are presented for laboratory waves breaking on a beach of slope 1:20 and for waves breaking over a submerged bar. A comparison of measurements using video and LDA techniques is also presented. The measurement of water levels and wave roller structures is accomplished by generating a video time series of the wave at a given horizontal position, from which the water levels and rollers structures are extracted.