Numerical Studies to Investigate Flow Behaviour of Two-Phase Liquid–liquid Flow in Microchannels

Microfluidic liquid–liquid extraction devices have unique advantages including lower fluid requirements and high extraction efficiency. In this work, we study the flow behaviour of two immiscible fluids in a cross-flow microchannel. The effect of different geometry that can influence the flow pattern is evaluated. Towards this, we compared the flow through a simple cross-flow microchannel with the flow through a microchannel modified with ridges. The ridges are arranged alternately as well as oppositely, and their effect is studied. Simulation studies were performed with COMSOL Multiphysics with diethyl ether and water as the two immiscible model fluids. Phase-field method coupled with the multiphase laminar flow was used to solve the velocity profile, pressure field and the dispersed phase fraction in the microchannels. The simulation results revealed the formation of slug flow within the microchannel. The presence of ridges will lead to a higher dispersion of the fluids leading to enhanced mass transfer between the phases.