Turbulent oscillatory flow along unidirectional current over square ribs

Abstract

The objective of this research is to examine the turbulent flow characteristics over a series of square rib elements under the combined action of surface wave and unidirectional current. The velocity data were analyzed to determine the distributions of the mean velocity, turbulent kinetic energy, Reynolds shear stress, and the contribution of burst-sweep cycles. These were used for the characterization of flow over square rib due to the superposition of surface waves of different frequencies and thereby compare the results with the current-only case. Mean velocity profiles over the rib roughness, illustrate the well-known downward shift from the flat surface data. Also, the thickness of turbulent boundary layer increases with the superposition of surface wave when compared to current-only flow. Particular attention is also given to understand the behaviour of higher-order moments to explicitly account for turbulent momentum transport characteristics over rib roughness under wave-current interactions.