Characterization of the Nonaerated Flow Region in a Stepped Spillway by PIV

ness height. The local flow resistance coefficient is calculated by application of the von Kármán integral momentum equation. The shear strain, vorticity, and swirling strength maps obtained from the mean velocity gradient tensor are presented. Also, the fluctuating velocity field is assessed. The turbulent kinetic energy map indicates the region near the pseudobottom (imaginary line joining two adjacent step edges) as the most active in terms of Reynolds stresses. The turbulence was found to be very intense with maximum levels of turbulence intensity from 0.40 to 0.65 measured near the pseudobottom. Finally, the quadrant analysis of the velocity fluctuations suggests the presence of strong outflows of fluid from the cavities as well as inflows into the cavities. It is conjectured that the mass transfer/exchange between cavities and main stream, play an important role in the high levels of turbulent energy observed. DOI: 10.1115/1.2354529