Feedback-free microfluidic oscillator with impinging jets
Feedback-free microfluidic oscillator with impinging jets
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DOI：
10.1103/physrevfluids.5.054202
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发表时间：
2020-05-13
影响因子：
2.7
通讯作者：
Gallaire, F.
中科院分区：
文献类型：
--
作者：
Bertsch, A.;Bongarzone, A.;Gallaire, F.
本文描述了一种基于面向撞击射流并在层流条件下运行的微流体振荡器。使用适当的微通道配置，可以在稳定且相等的入口流量条件下产生微尺度的脉动液体流，并且无需移动部件或外部刺激。已经开展了一项实验活动，使用传统微加工技术在硅中制造的振荡器结构。这使我们能够详细研究这些结构的主要几何参数对振荡频率的影响。研究发现，观察到的规则振荡范围取决于输出通道的几何形状，当添加输出通道扩展时，在很大的雷诺数 (Re) 范围内会发生高度规则的振荡。研究表明，自振荡频率的演变取决于撞击射流之间的距离和射流的平均速度。使用谱元法进行了直接数值模拟。计算出的染料浓度场和无量纲自振荡频率与实验结果吻合良好。模拟可以根据压力场和速度场详细描述自激振荡现象。
The present paper describes a microfluidic oscillator based on facing impinging jets and operating in laminar flow conditions. Using appropriate microchannel configurations, pulsatile liquid flows are generated at the microscale from steady and equal inlet flow conditions and without moving parts or external stimuli. An experimental campaign has been carried out, using oscillator structures manufactured in silicon using conventional microfabrication techniques. This allowed us to study in detail the impact of the main geometric parameters of these structures on the oscillation frequency. The observed range of regular oscillations was found to depend on the geometry of the output channels, with highly regular oscillations occurring over a very large range of Reynolds numbers (Re) when an expansion of the output channel is added. The evolution of the self-oscillating frequency was shown to be dependent on the distance separating the impinging jets and on the average speed of the jets. Direct numerical simulations have been performed using a spectral element method. The computed dye concentration fields and nondimensional self-oscillation frequencies compare well with the experiments. The simulations enable a detailed characterization of the self-oscillation phenomenon in terms of pressure and velocity fields.