Microfluidic mixing of low viscosity Boger fluids

Abstract

This study is focused on the development of low viscosity Boger fluids and on the investigation of their elasticity on emulsion formation. Non-Newtonian continuous phases (Boger fluids) made of two different molecular weight Polyacrylamide in water plus glycerol solutions were used. While, as Newtonian continuous phase, a water plus glycerol solution showing the same viscosity as the non-Newtonian one was prepared and as dispersed phase silicon oil was used. Visualization of these emulsions flowing through a micromixer was useful in order to extract quantitative informations of their behavior, such as the velocity profile and droplets’ size distribution. Then the formation of vortex upstream of a divergent-convergent configuration has been shown as the wall migration effect, which drives droplets away from the walls and toward the center of the microcapillary investigated.