Experimental and numerical investigation of the internal kinematics of a surf-zone plunging breaker

Very good agreement was found for all comparisons: free-surface elevations, velocity vector maps, velocity profiles and velocity-magnitude contours. However, some small discrepancies were observed. In the free-surface elevation comparisons, a slight time lag was observed in the numerical results and it is suggested that this was due to the small amount of smoothing applied in the BIM to enable it to continue to supply input data to the Navier-Stokes solver well beyond the breaking of the wave. In addition, some small differences were also found between the numerically predicted velocity distributions and those measured in the experiments. These disagreements occurred mostly in the aerated region and it is proposed that they could be caused by errors in the PIV velocity data due to air bubble effects. However, they could also be attributed to the fact that no turbulence model is used in the numerical scheme and it is these aerated areas where the turbulence levels are the highest.