Abstract
The diffusion field of a passive scalar in a circular jet opposing a uniform water flow is investigated using PIV and PLIF techniques. Experiments were carried out for three cases of jet to counter-flow velocity ratios; 2.6, 3.7,4.8. Due to the radial oscillation of the jet penetrating into the counter-flow, the rms concentration fluctuation is found to have a local maximum within the stagnating region. Another distinct indication of the jet meandering is the rms to mean concentration ratio, which shows a rapid enhancement near the stagnation point after maintaining a constant value of about 0.3.
