Machado Anaïs, Bodiguel Hugues, Beaumont Julien, Clisson Gérald, Colin Annie
Univ. Bordeaux, CNRS , Solvay, Lab. LOF UMR5258, Pessac, France.
Univ. Grenoble Alpes, CNRS , Lab. LRP UMR5520, F-38000 Grenoble, France.
Biomicrofluidics. 2016 Jul 5;10(4):043507. doi: 10.1063/1.4954813. eCollection 2016 Jul.
We study flows of hydrolized polyacrylamide solutions in two dimensional porous media made using microfluidics, for which elastic effects are dominant. We focus on semi-dilute solutions (0.1%-0.4%) which exhibit a strong shear thinning behavior. We systematically measure the pressure drop and find that the effective permeability is dramatically higher than predicted when the Weissenberg number is greater than about 10. Observations of the streamlines of the flow reveal that this effect coincides with the onset of elastic instabilities. Moreover, and importantly for applications, we show using local measurements that the mean flow is modified: it appears to be more uniform at high Weissenberg number than for Newtonian fluids. These observations are compared and discussed using pore network simulations, which account for the effect of disorder and shear thinning on the flow properties.
我们研究了使用微流体技术制备的二维多孔介质中水解聚丙烯酰胺溶液的流动情况，其中弹性效应占主导。我们关注半稀溶液（0.1%-0.4%），其表现出强烈的剪切变稀行为。我们系统地测量了压降，发现当魏森贝格数大于约10时，有效渗透率显著高于预测值。对流动流线的观察表明，这种效应与弹性不稳定性的开始相吻合。此外，对于应用而言重要的是，我们通过局部测量表明平均流动发生了改变：在高魏森贝格数下，它似乎比牛顿流体更均匀。使用孔隙网络模拟对这些观察结果进行了比较和讨论，该模拟考虑了无序和剪切变稀对流动特性的影响。
