Electrohydrodynamics of a viscous drop with inertia.
Electrohydrodynamics of a viscous drop with inertia.
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具有惯性的粘性液滴的电流体动力学。
DOI：
10.1103/physreve.93.053114
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Wei
中科院分区：
文献类型：
--
作者：
H. Nganguia;Yuan;Anita T. Layton;Ming;Wei
现有的大多数数值和理论研究的粘性液滴的电流体动力学都集中在爬行斯托克斯流制度，其中忽略了非线性惯性效应。在这项工作中，我们研究了惯性效应的粘性液滴在直流电场下的电变形使用一种新的二阶浸没界面方法。惯性效应用Ohnesorge数Oh来量化，电场用电毛细数Ca_{E}来表征。在临界Ca_{E}以下，小到中等的电场强度产生稳定的平衡液滴形状。我们发现，在一定的Ca_{E}，惯性效应引起更大的变形扁圆形液滴比长形液滴，与以前的结果在文献中一致。此外，我们的模拟结果表明，惯性效应的平衡液滴变形取决于方向的法向电应力的液滴界面：较大的液滴变形时，发现法向电应力指向外，和较小的液滴变形，否则。据我们所知，这种惯性对平衡液滴变形的影响在文献中还没有报道。在临界Ca_{E}以上，液滴变形不稳定，液滴往往分裂成许多子液滴。特别是，我们的Navier-Stokes模拟表明，对于我们使用的参数，（1）子液滴在惯性的存在下更大，（2）与蠕动流相比，液滴变形发展得更快，（3）具有惯性效应的液滴的电应力分布复杂。我们的研究结果表明，正常的电压力可能是一个有用的工具，在预测下降夹断扁变形。
Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca_{E}. Below the critical Ca_{E}, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca_{E}, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca_{E}, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations.