Experimental and numerical studies of emulsion formation in a microfluidic T-junction

Abstract

The production of water-in-oil (w/o) emulsions in T-junction microfluidic channels was studied through experiments and computational fluid dynamics (CFD). W/o emulsions were produced in the microchannels from deionised water and mineral oil. The interfacial tension of the system was controlled to ~ 0.003 N/m using oil-soluble surface active agent (surfactant). A 2-dimensional (2D) CFD model was setup for simulation of the generation of w/o emulsion in a 200µm wide T-junction microchannel. COMSOL Multiphysics, a program based on the finite element method (FEM), was used. The fluid-fluid interface was modelled using the conservative level set method (LSM), where the oil-water interface was implicitly represented by level set function. The simulated droplets differed in size from the droplets observed in experiments. The deviation between the CFD model and experiments was attributed to the modelling approach which excluded the variations in contact angle between the two fluids and the channel surface which occur in experimental conditions.