Experimental and numerical investigations on the mixing quality of a novel micromixer are conducted. A micromixer made by PDMS is fabricated to evaluate the mixing process in comparison with the numerical simulations. The main purpose of the present paper is to propose an efficient divergence–convergence based macromixer for low-Reynolds-number flows. The effect of inlet velocity (Reynolds number), number of mixing cycles and blockage ratio on the mixing performance of the micromixer is investigated. The results reveal that the mixing efficiency (ME) increases with injection velocity, number of cycles and blockage ratio. For the range of Reynolds number from 9 to 75, the Dean vortices are not formed, however, generation of expansion vortices is the main factor of mixing for Re > 19. It is demonstrated that the value of ME/ΔP (Pa −1 ) for the micromixer with three, four, five and six mixing cycles is 6.36, 2.23, 0.74, and 0.5, respectively. In addition, the micromixer with the blockage ratio of 0.25 reaches the mixing efficiency of 100%. Relatively high values of ME/ΔP makes the proposed micromixer suitable for practical applications in which the Reynolds number is less than 75.

中文翻译：

---

高效收敛-发散微混合器的数值和实验研究

对新型微混合器的混合质量进行了实验和数值研究。制造了由 PDMS 制成的微混合器，以与数值模拟比较来评估混合过程。本文的主要目的是为低雷诺数流动提出一种有效的基于发散收敛的宏观混合器。研究了入口速度（雷诺数）、混合循环次数和堵塞比对微混合器混合性能的影响。结果表明，混合效率（ME）随着注射速度、循环次数和堵塞率而增加。对于雷诺数 9 到 75 的范围，没有形成迪安涡，但是当 Re > 19 时，膨胀涡的产生是混合的主要因素。结果表明，具有三个、四个、五个和六个混合周期的微混合器的 ME/ΔP (Pa -1 ) 值分别为 6.36、2.23、0.74 和 0.5。此外，堵塞比为0.25的微混合器达到了100%的混合效率。相对较高的 ME/ΔP 值使所提出的微混合器适用于雷诺数小于 75 的实际应用。