CFD study on Taylor bubble characteristics in Carreau-Yasuda shear thinning liquids

Abstract

In the present study, Taylor bubble formation in two-phase gas-non-Newtonian Carreau liquid flowing through a confined co-flow microchannel is investigated. Systematic analysis are carried out to explore the influences of rheological properties, inlet velocities, and surface tension on Taylor bubble length, shape, velocity and liquid film thickness. Aqueous solutions of carboxymethyl cellulose (CMC) with different mass concentrations are considered as the non-Newtonian liquids to understand the fundamentals of flow behaviour. With increasing solution viscosity and liquid phase inlet velocity, Taylor bubble formation frequency and velocity increased, however, the bubble length was found to decrease. Velocity profiles inside the Taylor bubble and liquid slug were analyzed, and distinct velocity distributions were found for different CMC concentrations. Flow pattern maps are constructed based on inlet velocities for Carreau liquids in co-flow microchannel. This study essentially provides useful guidelines in designing non-Newtonian microfluidic system for precise control and manipulation of Taylor bubbles.