Flow patterns of immiscible liquid-liquid flow in a rectangular microchannel with T-junction

Highlight
• Visualization of flow patterns for three sets of immiscible liquids was done.
• A new flow pattern with steady wavy interface was found.
• A parameter for flow pattern maps generalization was proposed.
• Plug length and velocity were measured for different total flow rate.

Flow patterns of immiscible liquid-liquid flow in a rectangular microchannel with T-junction are presented in this paper. Three liquid-liquid flow systems are considered, viz. kerosene – water, paraffin oil – water and castor oil – paraffin oil. Different flow patterns such as parallel flow, slug flow, plug flow, dispersed (droplet) flow, and rivulet flow are observed for different velocity ratios. New flow pattern of the parallel flow with steady wavy interface (serpentine flow) has been found. Plug length and velocity are measured for the plug flow regime. It is shown that flow pattern maps based on Weber numbers for different liquid-liquid systems do not match well. Weber number multiplied by Ohnesorge number is proposed as a parameter to generalize flow maps. Flow maps based on this parameter are superposed well for all liquid-liquid systems of this work and experiments of Zhao et al. (2006).