Experimental and numerical investigations on characteristics of coaxial liquid cone in coflow focusing

The interfacial instability and flow patterns of coaxial liquid cone in a coflow focusing (CFF) process are investigated through the integration of experiments and numerical simulations. Based on the flow fields obtained quantitatively in numerical simulations, the startup process of focused coaxial liquid cone is established, and the streamlines of focusing stream are further compared with the potential flow model. The effects of main process parameters, including liquid flow rates, physical properties of materials, and geometrical parameters of CFF device on the cone morphologies, are given experimentally and numerically, and the local competition between the viscous shear stress and the interfacial tension on inner and outer cone interfaces is analyzed qualitatively through nondimensional parametric analysis. Moreover, through the particle tracing method in CFF experiments, the flow fields inside the liquid cone are obtained, with much attention paid to the recirculation flow occurring inside the inner liquid cone. The results show that the variation of liquid flow rates can manipulate the size of recirculation flow, and the balance of tangential shear stress makes main contributions to the formation of recirculation flow. This study provides significant guidance for the generation of microcapsules by the CFF technique in practical applications.

Automated summary

This study investigates the interfacial instability and flow patterns of a coaxial liquid cone in a CFF process through experiments and numerical simulations, providing important guidance for the generation of microcapsules using the CFF technique in practical applications.