Effects of wave–current interaction on the current profile

Wave–current laboratory experiments have shown that the logarithmic current profile observed in pure current flows is modified due to the presence of waves. When waves propagate opposite the current, an increase in the current intensity is achieved near the mean water level, while a reduction is obtained for following waves and currents. With the aim of analyzing these nonlinear effects along the whole water column, an Eulerian wave–current model is presented. In contrast to previously presented wave–current models, the present is able to include the variation of the free surface elevation due to the wave motion and the effect of a non hydrostatic pressure field. Therefore it does not restrict its application to waves in shallow waters. Moreover, the model is able to simulate all the possible angles between waves and currents.Several available experimental steady current profiles in combined flows, covering different current regimes, angles between waves and currents and different bed roughness, are considered in the model validation. In general, a good agreement between the measured and the computed profiles is obtained. The model is able to predict the differences observed between following and opposing waves, not only near the mean water level but also near the bottom. As shown in the experiments, the model reproduces the reduction of the apparent bed roughness observed in following cases with smooth bed and the increase in rough bed conditions. In order to have a better understanding of the wave–current interaction process, the model is applied to different combined flow cases. The results obtained are shown and discussed in the present paper.