Electrohydrodynamic instabilities in freely suspended viscous films under normal electric fields
Electrohydrodynamic instabilities in freely suspended viscous films under normal electric fields
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DOI：
10.1103/physrevfluids.6.103703
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发表时间：
2021-10-20
影响因子：
2.7
通讯作者：
Saintillan, David
中科院分区：
文献类型：
--
作者：
Firouznia, Mohammadhossein;Saintillan, David
流体-流体界面的电流体动力学不稳定性可以在各种微流体应用中被利用，以增强混合、复制良好控制的图案或产生特定尺寸的液滴。在这项工作中，我们研究了系统的稳定性和动力学的三个叠加层的两个不混溶流体受到正常的电场。根据泰勒-梅尔彻漏电介质模型，本体保持电中性，而净电荷积累在界面上。界面电荷动力学被捕获的欧姆传导，平流的流量，和有限的电荷弛豫的守恒方程。使用这个模型，我们进行了线性稳定性分析，并确定不同的模式的不稳定性，我们的特征系统的行为作为一个功能的相关无量纲组在每个模式。此外，我们使用边界元法进行数值模拟，研究非线性对长时间界面动力学的影响。我们演示了如何耦合的流动和表面电荷输运在不同模式的不稳定性可以引起非线性现象，如尖端流或捏成液滴的膜。
Electrohydrodynamic instabilities of fluid-fluid interfaces can be exploited in various microfluidic applications to enhance mixing, replicate well-controlled patterns, or generate drops of a particular size. In this work, we study the stability and dynamics of a system of three superimposed layers of two immiscible fluids subject to a normal electric field. Following the Taylor-Melcher leaky dielectric model, the bulk remains electroneutral while a net charge accumulates on the interfaces. The interfacial charge dynamics is captured by a conservation equation accounting for Ohmic conduction, advection by the flow, and finite charge relaxation. Using this model, we perform a linear stability analysis and identify different modes of instability, and we characterize the behavior of the system as a function of the relevant dimensionless groups in each mode. Further, we perform numerical simulations using the boundary element method to study the effect of nonlinearities on long-time interfacial dynamics. We demonstrate how the coupling of flow and surface charge transport in different modes of instability can give rise to nonlinear phenomena such as tip streaming or pinching of the film into droplets.