Turbulence Characteristics of Flow Under Combined Wave–Current Motion

Abstract

This paper describes an experimental study carried out in a laboratory flume with a smooth surface to investigate the effect of a surface wave on unidirectional current. The measured velocity data were analyzed within the framework of the phase averaging for combined wave–current flow and verified by velocity equations based on the phase-averaged Prandtl momentum-transfer theory. The results highlight the changes induced on the mean velocity profile, turbulence intensity, and Reynolds shear stress in a plane of symmetry due to the superposition of surface waves of different frequencies. Modifications in the mean velocities, the turbulence intensities, and the Reynolds shear stresses with respect to the current-only flow are explored. As the frequency of the surface waves in unidirectional current changes, the results show variations in the mean flow and in the turbulence statistics that may affect the local sediment mobility in the coastal region.