Asymptotic and numerical analysis of electrohydrodynamic flows of dielectric liquid.
Asymptotic and numerical analysis of electrohydrodynamic flows of dielectric liquid.
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介电液体电流体动力学流动的渐近和数值分析。
DOI：
10.1103/physreve.88.023003
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
D. Cho
中科院分区：
文献类型：
--
作者：
Y. Suh;K. Baek;D. Cho
对非极性液体在外加非均匀电场作用下的电流体动力学流动进行了渐近分析。感兴趣的区域覆盖了电极附近的块体和薄的离解层(DSL)。离子输运的外部(即整体)方程可以用线性形式表示，而内部(即DSL)方程则采用非线性形式。我们根据各种参数推导出一个简单的公式，该公式可以用来估计DSL驱动流与主体驱动流相比的相对重要性。然后，对圆柱形电极上的EHD流动进行了渐近数值求解。结果表明，在较大的几何尺度和较高的离子浓度下，EHD流动以体电荷诱导流为主。随着尺度和浓度的减小，DSL驱动的滑移速度增加，所产生的流动趋于主导区域，最终导致流动逆转。我们还进行了流动可视化实验来验证分析，通过参数调整，两种结果达到了很好的一致性。最后，基于实验解和数值解的比较，我们证明了自由离子的产生(解离)速率应该小于现有公式所预测的速率。
We perform an asymptotic analysis of electrohydrodynamic (EHD) flow of nonpolar liquid subjected to an external, nonuniform electric field. The domain of interest covers the bulk as well as the thin dissociation layers (DSLs) near the electrodes. Outer (i.e., bulk) equations for the ion transport in hierarchical order of perturbation parameters can be expressed in linear form, whereas the inner (i.e., DSL) equations take a nonlinear form. We derive a simple formula in terms of various parameters which can be used to estimate the relative importance of the DSL-driven flow compared with the bulk-driven flow. EHD flow over a pair of cylindrical electrodes is then solved asymptotically and numerically. It is found that in large geometric scale and high ion concentration the EHD flow is dominated by the bulk-charge-induced flow. As the scale and concentration are decreased, the DSL-driven slip velocity increases and the resultant flow tends to dominate the domain and finally leads to flow reversal. We also conduct a flow-visualization experiment to verify the analysis and attain good agreement between the two results with parameter tuning. We finally show, based on the comparison of experimental and numerical solutions, that the rate of free-ion generation (dissociation) should be less than the one predicted from the existing formula.