Effect of Jet Injection on Flow Structure in Local Pier Scour

Abstract

This study investigates experimentally the effect of jet injection on the flow structure around a pier-scour hole. Experiments are conducted with 1-jet, 3-jets and without jet injection under clear-water scour conditions. The results show that the jet(s) alter(s) the turbulent characteristics and vertical component of the velocity, causing a reduction of the strength of the down flow. A quadrant analysis for the Reynolds shear stress values reveals that the sweeps and ejections have the main contributions on the Reynolds shear stress production in the near-bed flow. The third-order correlations of velocity fluctuations show an obvious distinction for the jet injection experiments in comparison to that without injections, especially inside the scour hole.