Study the Effect of Seepage on the Higher Order Moment to Extract Information About the Turbulent Flow Structure in an Open Channel Flow

An experimental study was carried out to focus the effect of introduction seepage on different turbulent characteristics for an open channel flow. Test results with both suction and injection is presented and discussed to understand the extent of influence of seepage in the depth-wise direction. Particular attention was given on mean velocity, turbulence intensity, Reynolds shear stress, shear stress correlation, higher order moments and quadrant analysis. Two different Reynolds numbers (Re = 31000 and 47500) were used for each test condition. Reynolds numbers were chosen in order to keep flow condition as sub-critical (i.e. Froude numbers less than unity). The results from the analysis show that the effect of seepage on different turbulent characteristics is not restricted to the near-bed region but can be seen for most of the flow depth. Effect of injection on different turbulent characteristics is more evident with the lower flow rate, however the effect of suction seems to be independent of the flow rates. Results from the analysis of turbulent bursting events show clearly visible effect of seepage well beyond the near-bed region.