Numerical Investigation of Double Emulsion Formation in non-Newtonian Fluids using Double Co-Flow Geometry

Abstract

Abstract The paper presents a 2D axisymmetric numerical simulation in three phases to investigate a double Co-Flow microfluidic device's ability to produce double emulsions in both Newtonian and non-Newtonian ambient fluids. The Volume of fluid (VOF) method was utilized to perform an investigation of the creation of a double emulsion in a double Co-Flow geometry. The study utilized a model to examine how the size and generation frequency of double emulsions are impacted by various factors such as the velocity of the phases, viscosities, interfacial tension, and rheological properties of non-Newtonian fluids. The model predicted the process of emulsification successfully in dripping and jetting regimes and was used to predict the impacts of the velocity of the phases on the dimension, and frequency of compound droplets. As the inner phase's flow rate is raised, the size of the inner droplets rises, while the dimension of the outer droplets remains mostly unchanged. In contrast, growing the outer phase's flow rate leads to a reduction in the size of compound droplets. However, when the middle phase's flow rate is enhanced, the size of detached droplets in the outer and inner phases undergo opposite changes, i.e., decreasing and increasing in Newtonian and non-Newtonian fluids, respectively. Also, the results showed that in non-Newtonian fluids, smaller droplets are formed compared to Newtonian fluid, and the diameter of the double emulsions formed decreases, with the rise in the concentration of the non-Newtonian fluid.