Multidirectional vortices mixing in three-stream micromixers with two inlets

In this work, we design, fabricate and compare three types of three-stream curved-straight-curved (CSC) micromixers, including the full three-stream (FTS) CSC micromixer, the CSC microchannel with internal side-wall injection and the CSC microchannel with external sidewall injection. In the three-stream CSC micromixers, there is a core stream sandwiched by two cladding streams into the CSC channel with baffles from two inlets. The sandwichedstructure of streams and the multidirectional vortices due to flow separation and channel curvature contribute together to enhance mixing. We examine fluid mixing in the proposed micromixers by numerical simulation and using confocal spectral microscope imaging system. The present results show that the mixing efficiency increases without increasing the pressure applied much by the channel structure forming the sandwiched structure of streams. Besides, it is found that the FTS CSC micromixer is the preferable one among the micromixers considered.