  We inject with jet mixtures of ethanol and dissolved anise oil upward into
quiescent water with jet Reynolds numbers, 500<Re_0<810. Nucleation of oil
droplets, also known as the ouzo effect, follows from the entrainment and
mixing with ambient water, where the oil has much lower oil solubility than the
initial jet fluid. We experimentally investigate the local concentration during
solvent exchange near the turbulent/non-turbulent interface (TNTI) in the
quasi-2D turbulent jet. Using a light attenuation technique, we measure the
concentration fields for the nucleated oil droplets and the reference dye case.
  Combining conventional and conditional profiles, we show that the nucleation
of oil droplets is initiated near the TNTI, and penetrates into the turbulent
region as the jet travels downstream. Persistent nucleation not only sustains
the scalar dissipation but also leads to enhanced temporal fluctuations of the
concentrations till the downstream position. The p.d.f.s of the concentration
exhibit pronounced bimodal shapes near the TNTI and positively-skewed curves
toward the centerline, suggesting that the oil droplets nucleate across the
jet. We estimate the nucleation rate near the TNTI using a control volume
approach. We also model the concentration field of the nucleated oil using that
of the passive scalar and the ternary phase diagram of a water, ethanol, and
anise oil mixture.
  This study extends our previous work on the mean field, revealing more
details of the turbulent statistics induced by solvent exchange. The findings
shed new light on the interplay between mixing and nucleation in a quasi-2D
turbulent jet. We also provide the first modelling of solvent exchange in
turbulent flows with a simple model based on ethanol concentration and the
phase diagram.
