Electrically charged conducting drops revisited

“…12 Note also that the drops considered here are originally electroneutral and do not possess a charge, as those in the seminal works of Rayleigh and the following works. 42,43 Also, the present drops do not experience shearing electric tractions at their surfaces and the associated internal circulations or electrorotation, as the experiments reveal, which makes the situation here radically different from those considered (mostly for nonplanar spherical or spheroidal cases) in the literature. 44−49 The drop shape is described in the polar coordinates as…”

Section: Electric Maxwell Stress At the Drop Surfacementioning

confidence: 58%

“…In the case of ionic conductors, the approximation of a perfect conductor is appropriate when the charge relaxation time is much shorter than the characteristic hydrodynamic time associated with the rate of the evolution of the drop shape under the action of the electric field and capillarity . Note also that the drops considered here are originally electroneutral and do not possess a charge, as those in the seminal works of Rayleigh and the following works. , Also, the present drops do not experience shearing electric tractions at their surfaces and the associated internal circulations or electrorotation, as the experiments reveal, which makes the situation here radically different from those considered (mostly for nonplanar spherical or spheroidal cases) in the literature. − …”

Section: Electric Maxwell Stress At the Drop Surfacementioning

confidence: 75%

Evolution and Shape of Two-Dimensional Stokesian Drops under the Action of Surface Tension and Electric Field: Linear and Nonlinear Theory and Experiment

Granda

Plog

et al. 2021

Langmuir

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The creeping-flow theory describing evolution and steady-state shape of two-dimensional ionic-conductor drops under the action of surface tension and the subcritical (in terms of the electric Bond number) electric field imposed in the substrate plane is developed. On the other hand, the experimental data are acquired for drops impacted or softly deposited on dielectric surfaces of different wettability and subjected to an in-plane subcritical electric field. Even though the experimental situation involves viscous friction of drops with the substrates and wettability-driven motion of the contact line, the comparison to the theory reveals that it can accurately describe the steady-state drop shape on a non-wettable substrate. In the latter case, the drop is sufficiently raised above the substrate, which diminishes the three-dimensional effects, making the two-dimensional description (lacking the no-slip condition at the substrate and wettability-driven motion of the contact line) relevant. Accordingly, it is demonstrated how the subcritical electric field deforms the initially circular drops until an elongated steady-state configuration is reached. In particular, the surface tension tends to round off the non-circular drops stretched by the electric Maxwell stresses imposed by the electrodes. A more pronounced substrate wettability leads to more elongated steady-state configurations observed experimentally than those predicted by the two-dimensional theory. The latter cases reveal significant three-dimensional effects in the electrically driven drop stretching. In the supercritical electric fields (corresponding to the supercritical electric Bond numbers), the electrical stretching of drops predicted by the present linearized two-dimensional theory results in splitting into two separate droplets. This scenario is corroborated by the predictions of the fully nonlinear results for similar electrically stretched bubbles in the creeping-flow regime available in the literature as well as by the present experimental results on a substrate with slip.

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Rayleigh instability of charged drops and vesicles in the presence of counterions

Thaokar

Deshmukh

2010

Physics of Fluids

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Rayleigh instability of charged conducting drops, in the viscous regime, is analyzed in the presence of counterions in the surrounding fluid. The Rayleigh criterion for the instability is derived in the Debye–Huckel approximation. It is found that the critical charge for the instability is reduced in the presence of counterions. The analysis is carried out for charged vesicles, with symmetric double layers across the bilayer, and the critical charge for the instability is determined. It is found that vesicles can indeed become unstable at high surface potentials. These results should be important in biological systems, where cells, with charged membranes, are immersed in electrolyte solutions. Additionally, the expression for the decay rate for vesicles with charged bilayers should give better estimates for the correlation time of the shape fluctuations.

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Electrically charged conducting drops revisited

Cited by 3 publications

References 8 publications

Electrohydrodynamic behaviour of a drop subjected to a steady uniform electric field at finite electric Reynolds number

Electrohydrodynamic behaviour of a drop subjected to a steady uniform electric field at finite electric Reynolds number

Evolution and Shape of Two-Dimensional Stokesian Drops under the Action of Surface Tension and Electric Field: Linear and Nonlinear Theory and Experiment

Rayleigh instability of charged drops and vesicles in the presence of counterions

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