Turbulence properties of a vertical round jet in a wavy-crossflow environment

Abstract

The discharge of wastewater into coastal waters can be simplified as a turbulent jet under waves and currents. A laboratory study has been carried out to measure the instantaneous flow field of a vertical round jet under wavy-crossflow environment using an improved particle image velocimetry (PIV) technique. The phase-averaged streamlines are found to be the most chaotic at the wave trough phase. Temporal variation in fluctuating turbulent kinetic energy is explored. Results indicate a lack of distinctive patterns in fluctuation turbulent kinetic energy across wave phases, particularly in far field. This suggests that wave phases marginally affect jet width expansion, especially in the far field. Spatial variations in turbulent kinetic energy are examined and crossflow and wave period are also considered. It is found that decreasing relative wave-orbital velocity to crossflow velocity Rwc enhances maximum turbulent kinetic energy in the near field of the wavy-crossflow jet.