The Distortion of Aerosol Droplets by an Electric Field

O’Konski, Chester T.; Thacher, Henry C.

doi:10.1021/j150510a024

Cited by 196 publications

(81 citation statements)

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“…The degree of elongation is given as a balance between electrostatic energy, preferring a long, needlelike, drop, and surface tension, preferring a spherical object (Taylor, 1964). O'Konski and Thacher (1953) and later Allan and Mason (1962) obtained the following expression for small deformations of drops:…”

Section: A Dielectric Interfacesmentioning

confidence: 99%

Colloquium: Phase transitions in polymers and liquids in electric fields

Tsori

2009

Rev. Mod. Phys.

101

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The structure and thermodynamic state of a system changes under the influence of external electric fields. Neutral systems are characterized by their dielectric constant ε, while charged ones also by their charge distribution. In this Colloquium several phenomena occurring in soft-matter systems in spatially uniform and nonuniform fields are surveyed and the role of the conductivity σ and the linear or nonlinear dependency of ε on composition are identified. Uniform electric fields are responsible for elongation of droplets, for destabilization of interfaces between two liquids, and for mixing effects in liquid mixtures. Electric fields, when acting on phases with mesoscopic order, also give rise to block copolymer orientation, to destabilization of polymer-polymer interfaces, and to order-order phase transitions. The role of linear and nonlinear dependences of ε on composition will be elucidated in these systems. In addition to the dielectric anisotropy, existence of a finite conductivity leads to appearance of large stresses when these systems are subject to external fields and usually to a reduction in the voltages required for the instabilities or phase transitions to occur. Finally, phase transitions which occur in nonuniform fields are described and emphasis on the importance of ε and σ is given.

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Section: A Dielectric Interfacesmentioning

confidence: 99%

Colloquium: Phase transitions in polymers and liquids in electric fields

Tsori

2009

Rev. Mod. Phys.

101

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“…This problem, first studied by Wilson & Taylor (1925), was originally analyzed under the premise that normal electric stresses acting on an uncharged interface are responsible for deformations (O'Konski & Thacher 1953;Harris & O'Konski 1957). Normal stresses, however, can only result in prolate deformations, while experiments have been known to show both prolate and oblate shapes depending on material properties (Allan & Mason 1962).…”

Section: Introductionmentioning

confidence: 99%

A nonlinear small-deformation theory for transient droplet electrohydrodynamics

Das¹,

Saintillan²

2016

J. Fluid Mech.

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The deformation of a viscous liquid droplet suspended in another liquid and subject to an applied electric field is a classic multiphase flow problem best described by the MelcherTaylor leaky dielectric model. The main assumption of the model is that any net charge in the system is concentrated on the interface between the two liquids as a result of the jump in Ohmic currents from the bulk. Upon application of the field, the drop can either attain a steady prolate or oblate shape with toroidal circulating flows both inside and outside arising from tangential stresses on the interface due to action of the field on the surface charge distribution. Since the pioneering work of Taylor (1966), there have been numerous computational and theoretical studies to predict the deformations measured in experiments. Most existing theoretical models, however, have either neglected transient charge relaxation or nonlinear charge convection by the interfacial flow. In this work, we develop a novel small-deformation theory accurate to second order in electric capillary number O(Ca 2 E ) for the complete Melcher-Taylor model that includes transient charge relaxation, charge convection by the flow, as well as transient shape deformation. The main result of the paper is the derivation of coupled evolution equations for the induced electric multipoles and for the shape functions describing the deformations on the basis of spherical harmonics. Our results, which are consistent with previous models in the appropriate limits, show excellent agreement with fully nonlinear numerical simulations based on an axisymmetric boundary-element formulation and with existing experimental data in the small-deformation regime.

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“…However, to the best of our knowledge, the electrostatic problem of a truncated spheroid in the uniform electric field has no analytical solution. Therefore, we use the completeprolate-spheroid model for the geometrical form of marbles for which the electrostatic problem has been solved [28]. In this case the energy of conducting droplet W exerted on electric field E is given by …”

Section: Resultsmentioning

confidence: 99%

“…(For derivation of the third term see [28]). Since the mass and volume of the droplet are constant, the total energy in (1) is a function of a single variable, e, while ( ) It should be recalled that equation (1) At the same time, the scaling interrelation between r and the electric field may be found on the basis of the reasoning developed by Aussillous and Quéré [1].…”

Section: Resultsmentioning

confidence: 99%

Electrically Deformable Liquid Marbles

Bormashenko¹,

Pogreb²,

Stein³

et al. 2011

Journal of Adhesion Science and Technology

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Liquid marbles, which are droplets coated with a hydrophobic powder, were exposed to a uniform electric field. It was established that a threshold value of the electric field, 15 cgse, should be surmounted for deformation of liquid marbles. The shape of the marbles was described as a prolate spheroid. The semi-quantitative theory describing deformation of liquid marbles in a uniform electric field is presented. The scaling law relating the radius of the contact area of the marble to the applied electric field shows a satisfactory agreement with the experimental data.

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The Distortion of Aerosol Droplets by an Electric Field

Cited by 196 publications

References 0 publications

Colloquium: Phase transitions in polymers and liquids in electric fields

Colloquium: Phase transitions in polymers and liquids in electric fields

A nonlinear small-deformation theory for transient droplet electrohydrodynamics

Electrically Deformable Liquid Marbles

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