  Collisions between a stream of drops and a continuous jet of a different
liquid are experimentally investigated. In contrast to previous studies, our
work focuses on the effects of liquid miscibility and wettability on the
collision outcomes. Thus, miscible and immiscible liquids providing total and
partial wetting are used. We show that, as long as the jet surface tension is
smaller than the drop surface tension, the drops can be encapsulated by the
jet, providing the so-called drops-in-jet structure. The transitions between
the different regimes remain similar in nature with a capillary fragmentation
responsible for the jet break-up and an inertial fragmentation causing the
drops (and then possibly the jet) to break up. The dimensionless numbers
proposed in the literature to model the inertial fragmentation thresholds do
not bring the results obtained with different liquids at the same critical
value. We explain the reason via a detailed analysis of the collisions,
accounting for the drop and jet extensions and their kinetics. The drop
fragmentation is found to occur during the recoil phase, leading us to propose
a new dimensionless parameter that successfully reproduced all our experimental
data obtained with immiscible liquids. Finally we demonstrate that the most
dramatic change of the collision outcomes is produced by using drops that
totally wet the jet. In this case, the encapsulation of the drops cannot be
achieved, constituting a true limit to some applications based on the
solidification of the drops-in-jet structure.
