Dynamics of capillary-driven liquid-liquid displacement in open microchannels.
Dynamics of capillary-driven liquid-liquid displacement in open microchannels.
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DOI：
10.1039/c4cp03910f
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
Die Yang;M. Krasowska;Craig Priest;John Ralston
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文献类型：
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作者：
Die Yang;M. Krasowska;Craig Priest;John Ralston
液滴沿着填充有另一种不混溶液体的开放亲水性微通道自发扩散的动力学主要由毛细管驱动力和粘性阻力之间的竞争决定。虽然前一种力取决于通道的横截面和尺寸、两种液体之间的界面张力以及通道壁与两种液体之间形成的接触角，但后者由两种本体液体中的流体分子的运动引起。本文着重研究了外相（驱替相）粘度的影响。通常，随着置换相的粘度相对于置换相的粘度增加，液-液弯月面的速度降低。通过在相同几何形状的开放微通道中扩展先前建立的液体-蒸气系统的相关性（J.Phys.Chem.C，2011，115（38），18761-18769）来解释实验。液-液流动动力学与液体性质（例如粘度）之间的关系仍然不清楚。然而，通过采取自洽的经验方法来估计粘度对给定系统的流动动力学的影响，可以在特定的粘度比范围内获得实验系统的合理理论描述。
The dynamics of the spontaneous spreading of a liquid droplet along an open hydrophilic microchannel filled with another immiscible liquid is primarily determined by the competition between the capillary driving force and the viscous drag. While the former force depends on the channel cross-section and dimensions, interfacial tension between two liquids and the contact angle formed between the channel's wall and the two liquids, the latter arises from the motion of fluid molecules in the two bulk liquids. This paper focuses on the influence of the outer (displaced) phase viscosity. In general, as the viscosity of the displaced phase increases relative to the viscosity of the displacing phase, the velocity of the liquid-liquid meniscus decreases. The experiments were interpreted by extending a previously established correlation for liquid-vapour systems (J. Phys. Chem. C, 2011, 115(38), 18761-18769) in open microchannels of the same geometry. The relationship between the liquid-liquid flow dynamics and the properties of the liquids (e.g. viscosities) is still unclear. Nonetheless, by taking a self-consistent empirical approach to estimate the influence of the viscosities on the flow kinetics for a given system, it is possible to obtain a reasonable theoretical description for the experimental system over a specific range of viscosity ratios.