Active control of viscous fingering using electric fields
Active control of viscous fingering using electric fields
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DOI：
10.1038/s41467-019-11939-7
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发表时间：
2019-09-05
影响因子：
16.6
通讯作者：
Bazant, Martin Z.
中科院分区：
文献类型：
--
作者：
Gao, Tao;Mirzadeh, Mohammad;Bazant, Martin Z.
粘指现象是一种广泛观察到的现象，在两种流体的界面上，当粘性较低的相取代粘性较强的相时，就会发生类似手指的不稳定性。众所周知，这种不稳定性很难控制，特别是在给定粘度比和几何形状的情况下。在这里，我们通过实验证明了两种给定液体的粘性指指的主动控制，对于给定的几何形状和流速在Hele-Shaw细胞。控制是通过施加外部电场，利用沿流体表面的电渗透流动来实现的。根据电场方向的不同，诱导的二次电渗透流动或辅助或反对水力流动，有效地降低或增加流动阻力，从而控制界面稳定性。提出了明显的“电动变薄/增厚”机制来解释实验结果。线性稳定性的理论预测在实验中得到了广泛的不混溶电解质位移的证实。
Viscous fingering is a widely observed phenomenon, in which finger-like instabilities occur at the interface of two fluids, whenever a less viscous phase displaces a more viscous phase. This instability is notoriously difficult to control, especially for given viscosity ratio and geometry. Here we demonstrate experimentally the active control of viscous fingering of two given liquids, for given geometry and flow rate in a Hele-Shaw cell. The control is realized by taking advantage of electro-osmotic flows along the surfaces confining the fluid, via applying an external electric field. Depending on the direction of electric field, the induced secondary electro-osmotic flows either assist or oppose the hydraulic flow, effectively reducing or increasing the flow resistance, leading to the control of interface stability. The mechanism of apparent "electrokinetic thinning/thickening" is proposed to explain the experimental observations. Theoretical predictions of linear stability are confirmed experimentally for a broad range of immiscible electrolyte displacements.