In this paper, detailed experimental results are reported to study the effect of the surface wave of different frequencies on turbulent characteristics of flow over a regular array of cubical roughness. The velocity time series of current-only and combined wave-current flow is analyzed to obtain the distribution of first and the second order turbulence statistics, turbulent kinetic energy production, turbulent dissipation and kinetic energy fluxes at a fixed Reynolds number. To highlight the changes due to combined wave-current flow, a comparative study was made between the velocity profiles for current-only flow and those measured for combined wave-current flow. As expected, the rough profiles are shifted downwards with the amount equivalent to the roughness function (ΔU+), which was obtained directly from mean velocity profiles. Further, the thickness of turbulent boundary layer increases with the superposition of surface wave compared to current-only flow. Particular attention is also given to understand the behavior of kinetic energy flux to explicitly account for turbulent momentum transport characteristics over roughness under wave-current interactions.
- Cubical roughness