On-chip mixing of liquids with high-performance embedded barrier structure

Typical laminar fluids micro-mixing in novel micro-mixers is investigated in this work. Micro-channels based on the T-shaped channel with CBPs which are mounted on the channel bottom were considered for this purpose. Three different embedded micro-barriers with different CBPs sizes were proposed to induce the fluid stretching and the fluid twisting as a theory of chaotic mixing in the proposed micro-mixers. The effect of hydrodynamic fluid tortuosity on the mixing quality of fluids was investigated. Maxwell, Weissberg, Boudreau, and numerical methods for calculation of tortuosity were examined. Additionally, three different mixing indices were used to determine the quality of mixing for two streams inside the main channel. The results showed that the tortuosity calculated from the Maxwell method was closer to the hydrodynamic tortuosity obtained by CFD results. Moreover, when the embedded barriers become close to the asymmetric pattern, the hydrodynamic fluid tortuosity increases and so does the quality of mixing. This trend occurs because of the fluid twisting effect and increase in the lateral Peclet number inside the channel. In other words, there is a direct relationship between the hydrodynamic fluid tortuosity and the mixing index. Moreover, since the non-uniformly of velocity field within the cross-section inside the channel, the mixing index with 'cup mixing average' (MI3) shows a more realistic value compared with the mixing index evaluated based on standard deviation (MI1) or absolute mixing index (MI2). (C) 2020 Elsevier Ltd. All rights reserved.