Quantitative Evaluation of Mixing Efficiency of Split-and-Recombine Mixing Method

In this paper, we present the acceleration of mixing and chemical reaction by a split-and-recombine (SAR) mixing method quantitatively, which was performed by numerical computation using the heat fluid analysis software, Star-CD. The authors have newly defined the mixing efficiency, which is a quantitative measure of the mixing of two fluids. The calculated result of the mixing efficiency in SAR device with two different channel configurations, angled and curved channels, showed that the secondary flow is important in increasing mixing efficiency. The angled channel is more effective than the curved channel, because the secondary flow is much stronger in the angled channel. The abrupt increase in sectional area also increases mixing efficiency. The split angle at the split point in the SAR device also affects mixing efficiency, because the secondary flow becomes stronger with the split angle. The mixing efficiency was greater (about 1.3 times) with a split angle of 45 degrees than that with a split angle of 15 degrees. According to the above-mentioned results, the authors designed a three-successive-SAR device, whose mixing efficiency was approximately 7.5 times greater than that of straight channel. The present findings are different from the existing mixing increase concept of the SAR device, which produces many thin layers from two fluids.