Abstract
In this study, laboratory experiments are conducted in a two-dimensional flume with a 1-m-long sandbox in the middle of a slope. Using fluorescent sand tracers and core sample methods, the spatial and temporal variation in the mixing depths in the surf zone are investigated. The core samples are collected from the sand bed where the wave breaking and impinging are observed. The mixing depth is defined as the fluorescent intrusion depth from the bed profile at the time of core sampling with a cut-off value of 10 tracers. In the case of sediment accumulation, the mixing depth is measured from the initial bed profile. Moreover, each case of the experiments is simulated by a numerical model, Large Eddy Simulation (LES), to compare the mixing depths with the velocity field of horizontal bottom eddies. The simulation results of the surface elevations and velocity fields are verified using the measured data. The experiment results indicate that the spatial variation of the mixing depths show different trends depending on the wave breaking style. Moreover, the mixing depth variations are compared with the simulated results of the bottom horizontal eddies. The results indicate that the plunging breaker type of sediment mixing pattern in space within the wave breaking zone correlates with the spatial distribution of the maximum bottom horizontal eddies.
