Direct numerical simulation of electroconvective instability and hydrodynamic chaos near an ion-selective surface
Direct numerical simulation of electroconvective instability and hydrodynamic chaos near an ion-selective surface
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DOI：
10.1063/1.4818995
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发表时间：
2013-11-01
影响因子：
4.6
通讯作者：
Mani, A.
中科院分区：
文献类型：
--
作者：
Druzgalski, C. L.;Andersen, M. B.;Mani, A.
我们提出了一个全面的分析与电动系统中的电流体动力学混沌的离子选择性表面的运输过程。所考虑的系统是一个离子选择性表面和一个固定的水库之间的水性对称的二元电解质。传输是由外部电场驱动的。使用直接数值模拟（DNS）耦合Poisson-Nernst-Planck和Navier-Stokes方程在2D中，我们显示了显着的过渡流动行为从相干涡对完全混乱的多层涡结构与宽带能谱。此外，我们证明，这些漩涡可以喷射到域的大部分的正和负的自由电荷密度，并完全破坏传统上描述的扩展空间电荷区域的结构。由此产生的动力学行为提出了一个挑战，传统的渐近模型依赖于准电中性体假设。此外，我们第一次量化的相对重要性，由于在各种运输制度的粘性效应的能量耗散。最后，我们提出了一个框架的整体平均模型（类似于雷诺平均Navier-Stokes方程）的发展和评估的重要性，我们的DNS数据的基础上未封闭的条款。(C)2013 AIP Publishing LLC.
We present a comprehensive analysis of transport processes associated with electrohydrodynamic chaos in electrokinetic systems containing an ion-selective surface. The system considered is an aqueous symmetric binary electrolyte between an ion-selective surface and a stationary reservoir. Transport is driven by an external electric field. Using direct numerical simulations (DNS) of the coupled Poisson-Nernst-Planck and Navier-Stokes equations in 2D we show significant transitions in flow behavior from coherent vortex pairs to fully chaotic multi-layer vortex structures with a broadband energy spectrum. Additionally, we demonstrate that these vortices can eject both positive and negative free charge density into the bulk of the domain and completely disrupt the structure of the traditionally described extended space charge region. The resulting dynamical behavior poses a challenge for traditional asymptotic modeling that relies on the quasi-electroneutral bulk assumption. Furthermore, we quantify for the first time the relative importance of energy dissipation due to viscous effects in various transport regimes. Finally, we present a framework for the development of ensemble-averaged models (similar to Reynolds Averaged Navier-Stokes equations) and assess the importance of the unclosed terms based on our DNS data. (C) 2013 AIP Publishing LLC.