Deformation and breakup of Newtonian and non-Newtonian conducting drops in an electric eld
Deformation and breakup of Newtonian and non-Newtonian conducting drops in an electric eld
复制标题
DOI：
--
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
J. Ong
中科院分区：
文献类型：
--
作者：
J. Ong
本文用实验方法研究了均匀电场作用下牛顿和非牛顿导电液滴在周围流体中的变形和破裂。首先，我们研究了三种不同的情况下，牛顿流体对的相对电导率不同，即高导电滴，导电滴和轻微导电滴。牛顿流体的结果表明，当液滴的电导率相对于周围流体的电导率非常大时，这种高导电液滴的变形响应由电流体静力学理论很好地描述，特别是关于临界点的预测。特别地，当液滴与连续相电阻率的比值R小于10 5时，电流体静力学理论是相当令人满意的。在此基础上，研究了满足R<O（10 5）条件的高电导液滴的非牛顿效应对液滴变形和破碎的影响。当液滴或连续相为非牛顿流体时，高导电液滴在弱或中等电场强度下变得稳定。另一方面，当两相都是非牛顿流体时，根据零剪切速率粘度的比率，观察到更复杂的响应。虽然流变性质的影响是最小的所有功能远离破碎的临界条件或之前的不稳定性，非牛顿性质有显着的影响，在液滴爆裂，这是伴随着大的速度和速度梯度。特别是当液滴的零剪切速率粘度与周围流体的零剪切速率粘度之比远大于1时，液滴相的非牛顿性质增强了液滴的稳定性。相反，连续相的弹性恶化了液滴稳定性。同时，当零剪切速率粘度比远小于1时，连续相的弹性会产生稳定效应。研究了电阻率和粘度比对破碎模式的影响。当两个相邻相中的至少一个具有相当大的非牛顿性质时，出现尖端流。
In this article, we considered experimentally the deformation and breakup of Newtonian and non-Newtonian conducting drops in surrounding fluid subjected to a uniform electric eld. First, we examined three distinctive cases of Newtonian-fluid pairs with dierent relative conductivities, namely highly conducting drops, conducting drops and slightly conducting drops. The results on the Newtonian fluids demonstrated that when the conductivity of the drop is very large relative to that of the surrounding fluid, the deformation response of such highly conducting drops is described well by the electrohydrostatic theory, especially with regard to the prediction of the critical point. Specically, when the ratio of drop to continuous-phase resistivity, R, was less than 10 5 , the electrohydrostatic theory was quite satisfactory. Then, the non-Newtonian eect on the drop deformation and breakup was studied for highly conducting drops which satised the condition R<O (10 5 ). The highly conducting drop became stable in a weak or moderate eld strength when either the drop or the continuous phase was non-Newtonian. On the other hand, when both the phases were non-Newtonian, more complicated responses were observed depending on the ratio of zero-shear-rate viscosities. Although the eects of the rheological properties are minimal on all features away from the critical conditions for breakup or prior to the instability, the non-Newtonian properties have a signicant influence during drop burst, which is accompanied by large velocities and velocity gradients. In particular, when the ratio of the zero-shear-rate viscosity of the drop to that of the ambient fluid was much larger than unity, non-Newtonian properties of the drop phase enhanced the drop stability. Conversely, the elasticity of the continuous phase deteriorated the drop stability. Meanwhile if the zero-shear-rate viscosity ratio was much smaller than unity, the elasticity of the continuous phase produced a stabilizing eect. The eects of resistivity and viscosity ratios on the breakup modes were also investigated. When at least one of the two contiguous phases possessed considerable non-Newtonian properties, tip streaming appeared.