Turbulence statistics of flow due to wave–current interaction

The paper describes an experimental study carried out in a laboratory flume with a smooth surface to investigate the interactions of gravity waves and unidirectional current. The observations are particularly focused on the changes induced in the mean velocity profiles, turbulent intensity and turbulent shear stress due to superposition of different frequency of waves on turbulent flow. Quadrant analysis has been adopted to investigate the importance of events contributing to the Reynolds shear stress in the near bed region. It is observed that near the boundary the contribution to the total shear stress due to ejection and sweeping events changes with the superposition of waves. The mean time intervals of occurrence of both ejection and sweeping events are obtained from the measurements of fractional contributions to the total shear stress. The distribution of the time interval is found to change as a consequence of superposition of waves. The motivation of this study is to identify the changes of mean flow and turbulent events and to gain better understanding of the physics of flow due to wave–current interaction, which are responsible for sediment transport.