Vortex flow evolution in a growing microdroplet during co-flow in coaxial capillaries

Using micro-particle image velocimetry (mu PIV), the convective flow inside a silicone oil droplet was investigated in detail during its formation in coaxial capillaries under co-flow in a water/glycerol mixture continuous phase. The analysis of mu PIV measured flow field revealed that two characteristic flow areas exist in the droplet in formation: an inflow zone and a circulation zone. The intensity of vortex flow in these zones was estimated by calculating the average angular velocity of these vortices under the condition of no shear for different dispersed phase and continuous phase flow rates and for different viscosity ratios between the two phases. The evolution of the vortex flow pattern inside the droplet was investigated thoroughly all the way from the step of their formation to the step of the free-moving droplet. The results of this study are important for understanding the mixing processes inside the droplet at different stages of its formation. Published under an exclusive license by AIP Publishing.

Automated summary

This study used mu PIV to investigate the convective flow inside a silicone oil droplet during its formation in coaxial capillaries under co-flow in a water/glycerol mixture continuous phase. The analysis revealed the existence of two characteristic flow areas in the droplet: an inflow zone and a circulation zone. The intensity of vortex flow in these zones was estimated by calculating the average angular velocity of these vortices under different conditions.