Thermally modulated interaction of compound droplets in a confined shear flow

The study of the interactive dynamics of a double emulsion in a shear flow finds wide applications in different physicochemical processes and serves as a crude, yet simplistic approach toward mimicking cell dynamics, owing to its unique morphology. However, there had been an extensive exploration toward understanding the dynamics of a single compound droplet under the effect of external forcing agents; nevertheless, a trivial extension would not grant the more realistic outcome of multiple compound droplet interactions. The following study utilizes the diffuse interface-based phase-field formalism to numerically predict the different patterns obtained due to such interactions and infers how an imposed temperature gradient as well as the channel confinement can be systematically used to modulate these patterns in fluid flow. The possibility of conversion of one type of pattern to another form due to a simple tweak in some of the governing parameters is also presented. It is found that for a given imposed shear rate and an initial separation distance between the droplets, the patterns formed due to compound droplet interactions change from sliding-over motion for large confinement to pinch-off or breakup in tighter confinements under no temperature gradient. In the presence of an imposed transverse temperature gradient, asymmetry in surface tension along the fluid interfaces in the lateral direction is induced and newer pattern formations are observed.