In this study, we have proposed volume-preserving strategies to boost chaoticadvection and improve the mixing efficiency of serpentine micromixers. The proposed strategies revolve around the point that the volume of the micromixer is kept constant during the manipulation. The first strategy involves the utilization of a nozzle-diffuser (ND) shaped microchannel. Using this, the velocity of the fluids fluctuates in an alternating pattern, leading to additional chaotic advection, a decrease in the mixing path, and an increase in the mixing index. The second strategy uses non-aligned inlets to generate swirl inducing effects at the microchannel entrance, where the collision of two fluids generates angular momentum in the flow, providing more chaotic advection. These strategies proved to be effective in boosting the mixing efficiency over wide ranges of Re in which 60% enhancement (from 20.53% to 80.31%) was achieved for Re of 30 by applying an ND shaped microchannel, and 20% enhancement (from 12.71% to 32.21%) was achieved for a critical Re of 15 by applying both of the strategies simultaneously. Supplementary material for this article is available online

中文翻译：

---

提高蛇形微混合器混合效率的体积保持策略

在这项研究中，我们提出了体积保持策略，以促进混沌对流并提高蛇形微混合器的混合效率。所提出的策略围绕着微混合器的体积在操作过程中保持恒定这一点而展开。第一种策略涉及使用喷嘴扩散器 (ND) 形微通道。利用这一点，流体的速度以交替模式波动，导致额外的混沌平流、混合路径减少和混合指数增加。第二种策略使用未对齐的入口在微通道入口处产生涡流诱导效应，其中两种流体的碰撞在流动中产生角动量，提供更混乱的平流。这些策略被证明在提高 Re 的广泛范围内的混合效率方面是有效的，其中通过应用 ND 形状的微通道，Re 30 实现了 60% 的增强（从 20.53% 到 80.31%），以及 20% 的增强（从 12.71%通过同时应用这两种策略，对于 15 的临界 Re 实现了 32.21%）。本文的补充材料可在线获取