  We experimentally investigate the early-stage scalar mixing and transport
with solvent exchange in quasi-2D jets. We inject an ethanol/oil mixture upward
into quiescent water, forming quasi-2D turbulent buoyant jets and triggering
the ouzo effect with initial Reynolds numbers, Re_0=420, 840, and 1680. We
study starting jets with continuous injection and puffs with finite volume
injection. While both modes start with the jet stage, the puff exhibits
different characteristics in transport, entrainment, mixing, and nucleation.
  For the starting jets, the total nucleated mass from the ouzo mixture seems
very similar to that of the passive scalar total mass, indicating a primary
nucleation site slightly above the virtual origin above the injection needle,
supplying the mass flux like the passive scalar injection. With continuous
mixing above the primary nucleation site, the mildly increasing nucleation rate
suggests the occurrence of secondary nucleation throughout the entire ouzo jet.
For the puffs, although the entrainment and nucleation reduce drastically when
the injection stops, the mild mixing still leads to non-zero nucleation rates
and the reduced decay of the mean puff concentrations for the ouzo mixture.
  Adapting the theoretical framework established in \citet{Landel2012b} for
quasi-2D turbulent jets and puffs, we successfully model the transport of the
horizontally-integrated concentrations for the passive scalar. The fitted
advection and dispersion coefficients are then used to model the transport of
the ouzo mixture, from which the spatial-temporal evolution of the nucleation
rate can be extracted. The spatial distribution of the nucleation rate sheds
new light on the solvent exchange process in transient turbulent jet flows.
