ABSTRACT:

This paper presents experimental results of a turbulent jet vertically discharged into a flow field of regular waves, in the intermediate between deep and shallow water. The instantaneous velocity field of the turbulent jet was measured using the particle image velocimetry technique. Phase average method was used to extract the turbulent velocity from the PIV measurements. Four different wave heights were used to show the effects of wave heights on jet. The results suggest that the influence of wave height on the turbulent characteristics of jets is significant. The convection term is more sensitive than the turbulent diffusion term for the change of wave heights, and the value of the turbulent diffusion term is about 1/ of the value of the convection term, which shows that the effect of the turbulent diffusion term can't be ignored in time-average N-S equations.

INTRODUCTION

In the treatment project of wastewater discharged into sea, the wastewater is mixed with the ambient water by jets. Wave is the most familiar phenomena in coastal waters, so the interaction of a turbulent jet flow and waves has been an important problem. Although studies on jets in a stagnant environment and a cross flow have been intensively performed by experimental works and numerical models in the last several decades (e.g., Rajaratnam, 1976; Fischer et al, 1979; Li and Huai, 2002; Park et al, 2006), the understanding of interaction between jet and wave hasn't been enough. An early study on diffusion of effluence in a wave environment was performed by Shouto and Ti (1974). They found that the diffusion of the plume increases significantly with the existence of the waves. Chin (1987) investigated the influence of surface waves on a buoyant jet experimentally. He suggested that the primary influence of waves is in the region of the source.

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