Prediction and measurement of leaky dielectric drop interactions

Kach, Jeremy I.; Walker, Lynn M.; Khair, Aditya S.

doi:10.1103/physrevfluids.7.013701

Cited by 7 publications

(20 citation statements)

References 56 publications

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“…(2021); Kach et al. (2022) to dissimilar drops. We first evaluate the electrostatic interaction of two widely separated spherical drops.…”

Section: Methodsmentioning

confidence: 99%

“…These flows can be either cooperative or antagonistic to the dipolar interactions (Baygents, Rivette & Stone 1998;Saintillan 2008;Park & Saintillan 2010;) and prevent chaining (Ha & Yang 2000). Recently, the three-dimensional interactions of a pair of identical droplets were investigated by means of numerical simulations using the boundary integral method, asymptotic theory for large separations and spherical droplets (Sorgentone, Tornberg & Vlahovska 2019;) and experiments (Kach, Walker & Khair 2022). The systematic exploration of the effects of fluid properties and the droplet initial configuration revealed intricate relative motions that eventually lead to either droplet coalescence or indefinite repulsion; only if the droplets line-of-centres were initially perpendicular to the applied field direction and the electrohydrodynamic flow along the droplet surface were equator-to-pole, the drops' motion is eventually arrested and the drops remain at an equilibrium separation.…”

Section: Introductionmentioning

confidence: 99%

“…Asymmetry in terms of droplet size or properties is expected to increase the complexity of the droplet interactions; however, the problem has been studied only to a limited extent for small droplet deformations (Kach et al. 2022) or only configurations where droplets are aligned with the field (Zabarankin 2020). Here, we analyse the three-dimensional interactions of dissimilar drops using both theory and simulations.…”

Section: Introductionmentioning

confidence: 99%

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Tandem droplet locomotion in a uniform electric field

Sorgentone

Vlahovska

2022

J. Fluid Mech.

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An isolated charge-neutral droplet in a uniform electric field experiences no net force. However, a droplet pair can move in response to field-induced dipolar and hydrodynamic interactions. If the droplets are identical, the centre of mass of the pair remains fixed. Here, we show that if the droplets have different properties, the pair experiences a net motion due to non-reciprocal electrohydrodynamic interactions. We analyse the three-dimensional droplet trajectories using asymptotic theory, assuming spherical droplets and large separations, and numerical simulations based on a boundary integral method. The dynamics can be quite intricate depending on the initial orientation of the droplets line-of-centres relative to the applied field direction. Drops tend to migrate towards a configuration with line-of-centres either parallel or perpendicular to the applied field direction, while either coming into contact or indefinitely separating. We elucidate the conditions under which these different interaction scenarios take place. Intriguingly, we find that in some cases droplets can form a pair (tandem) that translates either parallel or perpendicular to the applied field direction.

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“…(2021); Kach et al. (2022) to dissimilar drops. We first evaluate the electrostatic interaction of two widely separated spherical drops.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tandem droplet locomotion in a uniform electric field

Sorgentone

Vlahovska

2022

J. Fluid Mech.

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“…The existing literature covers various degrees of complexity, starting from a pair of identical droplets at a distance d, aligned with an electric field E 0 ẑ, such that Θ ≡ arccos( d • ẑ) = 0 (Sozou 1975;Baygents, Rivette & Stone 1998), over droplets dissimilar in S, R, λ and size, to arbitrary orientations , as well as including the effects of small deformations or surfactants ). Kach, Walker & Khair (2022) proceed by applying the asymptotic theory to interactions between three, or, eventually, more droplets, and show an initial quantitative comparison with experiments. Now, SV, combining asymptotic theory and boundary integral numerics, provide a systematic investigation of the attractive or repulsive dynamics of dissimilar droplets depending on their initial alignment and distance in (d, Θ) space.…”

Section: Introductionmentioning

confidence: 99%

“…2021), as well as including the effects of small deformations or surfactants (Sorgentone & Vlahovska 2021). Kach, Walker & Khair (2022) proceed by applying the asymptotic theory to interactions between three, or, eventually, more droplets, and show an initial quantitative comparison with experiments.…”

Section: Introductionmentioning

confidence: 99%

An electrohydrodynamic dance of unequal partners

Maaß

2023

J. Fluid Mech.

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The dynamics of charge-free dielectric droplets under electric fields in weakly conducting fluids is relevant to a large range of technological and environmental applications. In Sorgentone & Vlahovska (J. Fluid Mech., vol. 951, 2022, R2), the authors investigate by asymptotic theory and boundary integral simulations the motility states of a pair of dissimilar droplets at an arbitrary orientation to the electric field and find a state of steady motility that is carefully balanced between repulsion and contact.

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Effectiveness and limitations of two drop studies to explain emulsion dehydration under modulated electric fields

2023

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Electrocoalescence has long been known for the separation of a water‐in‐oil emulsion. An associated challenge with electrocoalescers is the undesired noncoalescence and consequently chain formation of aqueous phase droplets. This leads to low separation efficiency and damage of electrical equipment. Recently Hasib et al. proposed an electric field modulated scheme that showed significant improvement in dehydration of water‐in‐oil emulsions. They investigated the range of modulation parameters when the scheme is most effective. The fundamental process in electrostatic dehydration of an emulsion is the interaction between a pair of water droplets. In the present study, two suspended aqueous drops in insulated oil experiments are compared for their behavior under unmodulated and modulated electric fields. Further, a model is developed and the experimental behavior under unmodulated and modulated electric fields is compared with numerical solutions. The model predicts the experimental observations accurately by balancing electrostatic, electrophoresis, dipolar, and resisting viscous drag forces, ignoring the end (bridge) effect during the contact. The study shows that the increase in the rate of dehydration of a water‐in‐oil emulsion under modulated electric fields with an increase in duty ratio and its near independence on the modulation time period can be explained by the two‐drop studies. However, several other processes such as multidrop interactions as well as scavenging of fine droplets by charged droplets created as intermediates in the interaction of two droplets cannot be explained by the two‐drop studies.

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Prediction and measurement of leaky dielectric drop interactions

Cited by 7 publications

References 56 publications

Tandem droplet locomotion in a uniform electric field

Tandem droplet locomotion in a uniform electric field

An electrohydrodynamic dance of unequal partners

Effectiveness and limitations of two drop studies to explain emulsion dehydration under modulated electric fields

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