Characterization of the Mixing Quality in Micromixers

The laminar flow patterns and mixing performance of two different micromixers have been investigated and quantified using CFD. The micromixer geometries consist of a channel with either diagonal or asymmetric herringbone grooves on the channel floor. The numerical results show that a single helical flow is produced for the diagonal mixer, whereas the herringbone mixer creates a double helical flow, composed of an alternating large and small vortex. Particle tracking of a tracer shows that very little convective mixing occurs in the diagonal mixer. However, in the herringbone mixer, very good mixing occurs. Quantitative analysis methods that are traditionally used for characterizing macro‐scale static mixers have been employed. Calculation of the variance of tracer dispersion and the stretching has shown to be well adapted for quantifying the mixing in the micromixers. However, methods based on the deformation rate appear to be less suitable. The results are in excellent agreement with previous experimental findings. Micromixers have a large potential of application in tasks, such as mixing, blending, emulsification, and suspension, as well as for use as reactors and also in combination with integrated heat exchangers. The mixing efficiency in microprocesses is therefore very important for the definition of process performance and product quality. In this study, the flow patterns and mixing performance of two micromixers with different geometries have been investigated and quantified using CFD. The results show that very different mixing qualities can be obtained with very small modification in the geometry.