Understanding the vortex dynamics in polymer solutions is one of keys for the flow control in a wide range of polymer-related material processing applications. Vortex is generated due to the viscoelasticity of polymer solution, even if no vortex formation is expected under Newtonian flow conditions. In addition, the chaotic vortices generated in viscoelastic fluids have been recently exploited to mix different fluid streams in microfluidic devices. Herein, we investigated the vortex dynamics in dilute polyethylene oxide) solutions at the junction region of Y-shaped microchannels, which have been frequently used to mix two fluid streams. We report the formation of two types of vortices: A vortex at the stagnation point of the junction (center) and a lip vortex at the upstream of the sharp corner. Fluorescent microscopy revealed that the vortex dynamics was significantly affected by the angle between the two upstream channels, polymer concentration, and flow rate. We expect that this work will be useful for understanding the viscoelastic flow in microchannels and for the future design of microfluidic devices such as microfluidic mixers.

中文翻译：

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稀聚合物溶液中Y形微通道交界处的涡旋动力学

了解聚合物溶液中的涡旋动力学是各种聚合物相关材料加工应用中流量控制的关键之一。即使在牛顿流动条件下预计不会形成涡旋，也会由于聚合物溶液的粘弹性而产生涡旋。另外，粘弹性流体中产生的混沌涡流最近已被用来在微流体装置中混合不同的流体流。在这里，我们研究了Y形微通道交界处的稀聚环氧乙烷溶液中的涡旋动力学，该溶液经常被用来混合两种流体。我们报告了两种类型的涡流的形成：在连接点（中心）停滞点的涡流和在尖角上游的唇形涡流。荧光显微镜显示，涡流动力学受到两个上游通道之间的角度，聚合物浓度和流速的显着影响。我们希望这项工作对理解微通道中的粘弹性流动以及对微流体装置（如微流体混合器）的未来设计很有用。