Numerical and experimental investigation on micromixers with serpentine microchannels

This paper aims at study and analysis on species mixing performance of micromixers with serpentine microchannels by numerical simulation and experiment in depth. Mixing experiments with blue ink and yellow ink were implemented for six micromixers, and three better structures (square-wave, multi-wave and zigzag) were picked for further simulation research. Lots of productive numerical analysis were carried out for studying the mixing performance for Reynolds number (Re) values in the range from 0.1 to 100. The mixing efficiency decreases while Re varies from 0.1 to 1, and increases while Re varies from 1 to 100. At the Re of 0.1 and 100, the mixing performance of three structures is similar. Vortices, transversal flows and chaotic advection were produced with the increase of Re. Compared with the multi-wave micromixer and the zigzag micromixer, the square-wave micromixer is more efficient on mixing duo to its more sharp turns and longer path of the flow with Re being between 0.1 and 100. The results also show that the square-wave micromixer has higher pressure drops than the other two because of more sharp turns. Each square-wave unit enhances mixing obviously with the increase of Re and at a certain Re the former unit has a stronger effect on mixing than the latter. When Re is more than 100, the mixing efficiency can reach above 95% with a moderate pressure drop less than 50 kPa. Both experiment and simulation results demonstrated that the square-wave serpentine micromixer is flexible, effective, easily fabricated and integrated to a microfluidic system.