AC electrohydrodynamic instabilities in thin liquid films

Roberts, Scott Alan; Kumar, Satish

doi:10.1017/s0022112009006843

Cited by 86 publications

(67 citation statements)

References 63 publications

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“…The above expression is chosen because it conserves the root mean square of the potential as the parameter δ is varied (in contrast to the form adopted by Roberts and Kumar [36]). …”

Section: Problem Formulationmentioning

confidence: 99%

“…When dealing with simple interfaces, one typically uses h q and the interfacial charge Q q to characterize the state of the system [36,39]. Our problem is more complicated due to the potential discontinuity, and needs a third variable to be fully described.…”

Section: B Linearized Evolution Equationsmentioning

confidence: 99%

“…However, since the forcing electric terms are periodic in time and our system is linear, we may use techniques derived from the Floquet theorem to compute the growth rate s of any perturbation. We will briefly outline these techniques here, mostly following Klausmeier [50] (see also [36,39,51]). …”

Section: Growth Rate: Floquet Analysismentioning

confidence: 99%

See 2 more Smart Citations

Instability of a fluctuating membrane driven by an ac electric field

Seiwert

Vlahovska

2013

Phys. Rev. E

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Shape fluctuations of a planar lipid membrane in an AC electric field are investigated using a zerothickness electro-mechanical model, which accounts for membrane conductivity and capacitance, and asymmetry in the properties of the fluids separated by the membrane. The linear stability analysis shows that unlike the case of DC electric field, a purely capacitive membrane can be destabilized in an AC electric field. The theory highlights that the instability originates from electric pressure exerted on the membrane.

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“…The above expression is chosen because it conserves the root mean square of the potential as the parameter δ is varied (in contrast to the form adopted by Roberts and Kumar [36]). …”

Section: Problem Formulationmentioning

confidence: 99%

Section: B Linearized Evolution Equationsmentioning

confidence: 99%

See 1 more Smart Citation

Instability of a fluctuating membrane driven by an ac electric field

Seiwert

Vlahovska

2013

Phys. Rev. E

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“…Moreover, the influence of AC fields has been studied theoretically and has been shown to allow further control of the fluid-fluid interfaces in bilayer and trilayer liquid films -see Roberts & Kumar [28,29].…”

Section: Introductionmentioning

confidence: 99%

Electrostatically induced mixing in confined stratified multi-fluid systems

Cimpeanu

Papageorgiou

2015

International Journal of Multiphase Flow

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Electrostatic control mechanisms underpin a wide range of modern industrial processes, from lab-ona-chip devices to microfluidic sensors for security applications. During the last decades, the striking impact of fluid interface manipulation in contexts such as polymer self-assembly, micromanufacturing and mixing in viscous media has established the field of electrically driven interfacial flows as invaluable.This work investigates electrostatically induced interfacial instabilities and subsequent generation of nonlinear coherent structures in immiscible, viscous, dielectric multi-layer stratified flows confined in channels with plane walls. The present study demonstrates theoretically that interfacial instabilities can be utilized to achieve efficient mixing in different immiscible fluid regions. This is accomplished by electrostatically driving stable flows far from their equilibrium states to attain time-oscillatory and highly nonlinear flows producing mixing. The nonlinear electrohydrodynamic instabilities play the role of imposed background velocity fields or moving device parts in more traditional mixing protocols.Initially, simple yet efficient on-off voltage protocols are investigated and subsequently symmetrybreaking voltage distributions are considered and shown to considerably enhance the achieved level of mixing. Both two and three-dimensional flows, containing realistic fluid configurations (water and oils), are computed using direct numerical simulations based on the Navier-Stokes equations. Such numerical investigations facilitate the quantitative study of the flow into the fully nonlinear regime and constitute the basis of optimization methods in the context of microfluidic mixing applications in two-and three-dimensional geometries.

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“…It is found that the elasticity increases both the maximum growth rate and the corresponding wave number. In their study of AC electrohydrodynamic instabilities in thin liquid films, Roberts and Kumar [13] applied lubrication theory to examine the possibility of using AC electric fields to exert further control over the size and the shape of the pillars. They found that, for perfect dielectric films, linear stability analysis shows that the influence of an AC field can be understood by considering an effective DC field.…”

Section: Introductionmentioning

confidence: 99%

Electrohydrodynamics Instability of Three Periodic Streaming Fluids through Porous Media

Alkharashi¹

2015

OALib

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In this work, the effect of transverse horizontal electric field on the stability of three layers of immiscible liquids is illustrated. The fluids are subjected to a uniform horizontal electric field. Analytical and numerical simulations of this system of linear evolution equations are performed. The solutions of the linearized equations of motion and the boundary conditions lead to deriving two simultaneous Mathieu equations of damping terms having complex coefficients. The effects of the streaming velocity, the permeability of the porous medium, and the electrical properties of the flow on the instability are investigated. In the case of uniform velocity, it is found that electric field has a stabilizing influence on the stability criteria. When the periodicity of the velocity is considered, the method of multiple scales is applied to obtain stability solution for the considered system. It is found that the phenomenon of the dual role is found for increasing the permeability parameter. In addition it is found that the velocity of the middle layer has a destabilizing effect whereas the dielectric constant ratio has an opposite influence to the stability of the fluid layers.

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AC electrohydrodynamic instabilities in thin liquid films

Cited by 86 publications

References 63 publications

Instability of a fluctuating membrane driven by an ac electric field

Instability of a fluctuating membrane driven by an ac electric field

Electrostatically induced mixing in confined stratified multi-fluid systems

Electrohydrodynamics Instability of Three Periodic Streaming Fluids through Porous Media

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