Numerical investigation of centrifuge-trapping technique for generating gas–liquid flows in microchannels

Abstract

We have recently presented a novel approach (called the centrifuge-trapping method) based on a microfluidic structure for the generation of stratified flow and slug flow for biochemical applications based on centrifugal microfluidics. The technique relies on stratifying liquid into a spiral channel using centrifugal force and trapping bubbles between liquid plugs to form a slug flow. In this study, we comprehensively characterize the fluidic behavior of the system using a multiphase numerical model. The model is first validated by experiments and then used to evaluate the hydrodynamical effects of the system. Pressure fluctuation of the liquid plugs in the microchannel shows high stability of slug flow in rotational velocity ranging from 350 to 1000 RPM. The mixing efficiency of two liquids injected into the spiral channel is evaluated in generated stratified and slug flows. The results show that slug flow can be effectively utilized to enhance the mixing efficiency by more than 30% compared to single-phase or stratified flow. The formation of secondary flows into the liquid plugs is the main reason for elevated mixing.