The influence of wave acceleration and volume on the swash flow driven by breaking waves of elevation

We study the swash flow driven by breaking waves of elevation using two sets of large-scale experiments with a focus on understanding how wave properties control the flow evolution on the beach. In the first set of experiments, we test solitary waves and waveforms that have the same acceleration phase and wave height as the solitary waves, but an elongated deceleration phase. The results show that the run-up and the flow in the immediate vicinity of the moving shoreline are similar, showing that the shape of the wave acceleration phase controls these swash flow parameters. In the second set of experiments, we test waves generated by custom wavemaker trajectories (previously reported in Baldock et al., 2019) in which the wave-integrated volume flux, wave height, and wave period are varied. The results show that waveforms with the same wave-integrated volume flux produce nearly identical downrush flow despite having different wave heights and periods. Finally, we present dimensionless plots of swash flow that illustrate the utility of separate scalings for uprush and downrush flow, based on the wave acceleration and wave-integrated volume flux, respectively.