Particle alignment in a viscoelastic liquid flowing in a square-shaped microchannel
Particle alignment in a viscoelastic liquid flowing in a square-shaped microchannel
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DOI：
10.1039/c3lc50679g
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发表时间：
2013-01-01
期刊：
影响因子：
6.1
通讯作者：
Maffettone, Pier Luca
中科院分区：
文献类型：
--
作者：
Del Giudice, Francesco;Romeo, Giovanni;Maffettone, Pier Luca
我们证明了利用纯粘弹性效应在具有正方形横截面的直微通道中实现3D颗粒聚焦的可能性。通过考虑弹性的、恒定粘度的PVP（聚乙烯吡咯烷酮）水溶液作为悬浮液来进行实验。研究了几种流速和两种通道尺寸（具有固定的颗粒尺寸与通道尺寸比）。一种新的技术相结合的颗粒跟踪测量和数值模拟被用来重建的位置的流动颗粒的通道横截面。结果表明，对于所有的实验条件下，颗粒迁移向通道中心线。更高的流速可以增强流动聚焦。测量的颗粒分数可以根据一个单一的无量纲参数重新缩放，如文献中已经报道的圆柱形通道的情况。这样得到的主曲线可以用作预测所需聚焦长度的指导。还讨论了入口对聚焦通道长度的影响。最后，类比和与以前类似的作品的差异进行了讨论。
We demonstrate the possibility to achieve 3D particle focusing in a straight microchannel with a square cross-section by exploiting purely viscoelastic effects. Experiments are carried out by considering an elastic, constant-viscosity aqueous solution of PVP (polyvinylpyrrolidone) as the suspending liquid. Several flow rates and two channel dimensions (with a fixed particle size to channel dimension ratio) are investigated. A novel technique combining particle tracking measurements and numerical simulations is used to reconstruct the position of the flowing particles over the channel cross-section. The results show that, for all the investigated experimental conditions, particles migrate towards the channel centerline. Flow-focusing is enhanced by higher flow rates. The measured particle fractions can be rescaled according to a single dimensionless parameter, as already reported in the literature for the case of cylindrical channels. The so-obtained master curve can be used as a guide to predict the required focusing length. The effect of the entrance on the focusing channel length is also addressed. Finally, analogies and discrepancies with similar previous works are discussed.