Dissipative Flow Structures within Near-Wall Turbulence-Producing Events

Abstract

The high turbulent energy production rates in near-wall shear-driven turbulence are attributed to two types of transient flow events commonly termed ejections and sweeps. These motions possess length and time scales that make them accessible to direct measurements at low and moderate Reynolds numbers. Although the energy-producing aspects of the ejection/sweep flow patterns have been emphasized, it will be shown that these are also associated with intense and localized viscous dissipation which often result in the net removal of turbulent energy from the fluctuating field. The dissipative aspects of the ejections and sweeps contribute to the intensification of turbulent vorticity field in the vicinity of the wall.