Wakes and higher-order turbulence around circular cylinder of different diameters are investigated using particle image velocimetry measurements. The cylinder Reynolds number (Red) is defined by the depth averaged velocity, cylinder diameter and kinematic viscosity. The influence of Red on third-order moment of velocity fluctuations, turbulent kinetic energy (TKE) flux, TKE budget and turbulent length scales are presented. The intermittency factor and quadrant analysis around the cylinders are discussed for Red values ranging from 12,600 to 21,000. Intermittency factor increased with Red. Red effect modulated the energy budget mainly near free surface upstream and near bed downstream. Stream-wise and transverse TKE fluxes decreased significantly with Red, but not the vertical flux. Stream wise skewness changed sign from positive to negative with a certain critical distance on downstream, while vertical skewness showed reversed with Red. Negative stream-wise skewness and positive vertical skewness indicate the occurrence of ejection events. Production and dissipation rates increased with Red on the downstream, whereas opposite trend was observed for dissipation on the upstream. Increase of Red led to increase in Kolmogorov length-scale much higher on the upstream than downstream, whereas it showed depleting effect on Taylor's length-scale on upstream and increasing effect on the downstream. Ejection and sweep events were more prominent in the downstream near the cylinder than upstream with higher values of shear stress on the downstream. The sum of shear stress contributions of all quadrant events increased consistently with increase in Red near the cylinder.

In this paper, detailed experimental results are reported to study the effect of the surface wave of different frequencies on unidirectional current over the bed-mounted train of rib roughness. The model roughness used in this study is transverse square ribs that lengthened across the entire width of the recirculating wave channel. The center-to-center rib pitch (P) was constant during the experiments, thus generating a broad range of near-bed flow patterns for each of the three different surface wave frequencies studied here. The relative submergence associated with the roughness height (k) was 8, which fall in the category of large roughness. Velocity measurements were conducted using acoustic Doppler velocimeter (ADV), and a surface wave of different frequencies was generated using the plunger-type wavemaker. The measured velocity data were analyzed to determine the relative importance of mean flow over the train of rib roughness. Mean velocity profiles illustrate the well-known downward shift from the flat surface data of the semi-logarithmic portion of the law of the wall. The width of the turbulent boundary layer increases with the superposition of surface wave compared to that of the current-only flow. The results also show that the mean reattachment length decreases due to the superposition of surface wave on unidirectional current.

An exact solution of oscillatory Ekman boundary layer flow bounded by two horizontal flat plates, one of which is oscillating in its own plane and other at rest, is obtained. The effect of coriolis force on the resultant velocities and shear stresses for steady and unsteady flow has been studied.