The present study is to investigate the mechanism of turbulent fluctuation between regular progressive wave and neutrally buoyant horizontal round jet experimentally. A Particle Image Velocimetry (PIV) technique was employed to measure the instantaneous velocity field of the turbulent jet under wave environment. The mean flow and RMS (Root-Mean-Square) velocity fluctuation were extracted using the phase-averaged method of all instantaneous velocity maps located at that spatial location. Three different incident wave heights were used to examine the effects of wave amplitude on the interactions of a turbulent jet with water waves. The agreement of our experimental data to the similar profiles suggested by previous studies was discussed. The experimental results showed that the jet widths of the mean flow and RMS velocity fluctuation were significantly increased and shifted when jet was under the wave environments. The wave phase has an insignificant influence on the mean velocity field, but it affects the turbulent fluctuation field when jet under different wave motion phase.
Turbulent jets discharged into a wave environment have been an important problem to a wide spectrum of engineering practice, including hydraulic engineering, environmental engineering, coastal and ocean engineering, and the power industry. Primary examples are the outfalls located along a coastline such as the discharge of cooling water from a power plant cooling system into shallow water, and the treated/untreated discharge of waste water into the coastal water from municipality in a coastal region. It is of great concern to engineers, industry and government regulators that waste effluence disposed into a large water body needs to be effective in mixing and to maintain an acceptable level of concentration. In addition, as a wavy free surface exists near a turbulent jet, the behavior of the jet will change significantly.
