The simulated test and depth averaged flow velocity shows the same trend as in the measurements and increases towards the shoreline (\autoref{fig:Deltaflume2006_T01_default_fig5.eps}). However, in the simulation the cross-shore range with a higher offshore mean flow is smaller and extends less far seaward than in the measurements. This is possibly explained by differences in measured and simulated profile development (\autoref{fig:Deltaflume2006_T01_default_fig13.eps}) or inaccurate measurements. In addition, another explanation may be found in the incorrect modelling of the roller energy dissipation. Simulations (not shown) with a smaller roller dissipation rate revealed that roller energy in the inner surf increases, leading to higher return flow over a broader cross-shore range. 
Long waves contribute to the time and depth averaged flow close to the shoreline. The contribution of long waves to the mean flow is explained by on average larger water depths during the interval associated with shoreward flow velocities in relation to the interval with offshore flow velocities. Considering continuity and a uniform vertical structure of the long wave flow this means a time and depth averaged offshore directed flow should be present. 
Nonlinear waves may cause onshore sediment transport presuming non-uniform sediment stirring over the wave cycle and a positive correlation between sediment suspension and the intra wave flow. In order to include the wave averaged effect of nonlinear waves on the sediment transport a mean flow $u_{A}$ is computed, which is added to the mean (Eulerian) flow $U_{m}$ (see Van Thiel de Vries et al., 2009 for more details). The simulated time averaged flow associated with nonlinear waves shows a comparable evolution as in the measurements but is overestimated especially closer to the dune face. Near the shoreline the wave skewness related sediment transport vanishes (\autoref{fig:Deltaflume2006_T01_default_fig3.eps}) since waves develop towards fully saw tooth shaped bores that have negligible skewness.
The orbital flow velocity (\autoref{fig:Deltaflume2006_T01_default_fig6.eps}) is favourably predicted by the model. The short wave orbital flow velocity is slightly overestimated whereas the long wave orbital flow is underestimated. The underestimation of the simulated long wave orbital flow corresponds well to the slight underestimation of the observed long wave water surface variance.