Electrohydrodynamic-induced interactions between droplets

Das, Santanu; Dalal, Amaresh; Tomar, Gaurav

doi:10.1017/jfm.2021.120

Cited by 20 publications

(16 citation statements)

References 77 publications

(174 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the past couple of decades, there has been a growing interest in investigating droplet dynamics under electrical field, broadly under the scope of droplet electrohydrodynamics (EHD), via extensive theoretical, experimental, and numerical investigations. [32][33][34][35][36][37][38][39][40][41] In electrically mediated flows, droplet breakup is a well-known phenomenon, [42][43][44][45][46][47][48] preceding large deformation at high electrical capillary number, Ca E , signifying a decisive dominance of the electric stress over capillary stress. Fundamentally, in electric field, the droplet deforms to a new shape that is typically characterized by a discriminating function f T (R, S, l), originally introduced by Taylor, 49 where R, S and l are the ratios of electrical conductivity, permittivity and viscosity, respectively, of the droplet and the continuous phase.…”

Section: Introductionmentioning

confidence: 99%

Electrically modulated relaxation dynamics of pre-stretched droplets post switched-off uniaxial extensional flow

Behera

Chakraborty

2022

Soft Matter

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

Electrically modulated relaxation dynamics of pre-stretched droplets post switched-off uniaxial extensional flow

Behera

Chakraborty

2022

Soft Matter

View full text Add to dashboard Cite

show abstract

“…2019; Li et al. 2020; Das, Dalal & Tomar 2021). Garzon, Gray & Sethian (2018), in a more recent study, examined the partial coalescence phenomena of drops subjected to an electric field and analysed the consequent alterations in the size of the satellite drop.…”

Section: Introductionmentioning

confidence: 99%

“…Electrically mediated drop coalescence (or electro-coalescence) has emerged as a very active research topic in recent times, particularly keeping in purview its growing technological importance and the associated unaddressed scientific questions. These reported studies, however, were mostly restricted to the viscous-dominated regime (Mousavichoubeh, Ghadiri & Shariaty-Niassar 2011;Mousavi, Ghadiri & Buckley 2014;Mhatre et al 2015b;Santra, Mandal & Chakraborty 2018;Santra et al 2019;Li et al 2020;Das, Dalal & Tomar 2021). Garzon, Gray & Sethian (2018), in a more recent study, examined the partial coalescence phenomena of drops subjected to an electric field and analysed the consequent alterations in the size of the satellite drop.…”

Section: Introductionmentioning

confidence: 99%

Electric-field-mediated morpho-dynamic evolution in drop–drop coalescence phenomena in the inertio-capillary regime

Behera

Chakraborty

2023

J. Fluid Mech.

View full text Add to dashboard Cite

When two drops collide, they may either exhibit complete coalescence or selectively generate secondary drops, depending on their relative sizes and physical properties, as dictated by a decisive interplay of the viscous, capillary, inertia and gravity effects. Electric field, however, is known to induce distinctive alterations in the topological evolution of the interfaces post-collision, by influencing a two-way nonlinear coupling between electro-mechanics and fluid flow as mediated by a topologically intriguing interfacial deformation. While prior studies primarily focused on the viscous-dominated regime of the resulting electro-coalescence dynamics, several non-intuitive features of the underlying morpho-dynamic evolution over the intertio-capillary regime have thus far remained unaddressed. In this study, we computationally investigate electrically modulated coalescence dynamics along with secondary drop formation mechanisms in the inertio-capillary regime, probing the interactions of two unequal-sized drops subjected to a uniform electric field. Our results bring out an explicit mapping between the observed topological evolution as a function of the respective initial sizes of the parent drops as well as their pertinent electro-physical property ratios. These findings establish electric-field-mediated exclusive controllability of the observed topological features, as well as the critical conditions leading to the transition from partial to complete coalescence phenomena. In a coalescence cascade, an electric field is further shown to orchestrate the numbers of successive stages of coalescence before complete collapse. However, an increase of the numbers of cascade stages with the electric field strength and parent droplet size ratio is non-perpetual, and the same is demonstrated to continue until only a threshold number of cascade stages is reached. These illustrations offer significant insights into leveraging the interplay of electrical, inertial and capillary-driven interactions for controllable drop manipulation via multi-drop interactions for a variety of applications ranging from chemical processing to emulsion technology.

show abstract

“…Such deviations from a concentric ideality essentially stem from the fact that, despite highly precise controls exercised during droplet generation, inevitable differences in the viscous drag acting at the two interfaces (Utada et al 2005;Nabavi et al 2015;Yu et al 2019), as well as property contrasts between the inner and the outer drops, may result in obvious deviations from concentricity. This, in turn, leads to simultaneous deformation and translation of the compound drop, as against the case of a concentric one that undergoes deformation without any net migration under a uniform external electric field (Baygents, Rivette & Stone 1998;Das, Dalal & Tomar 2021;Sorgentone et al 2021). While the compelling need of rationalizing this deficit in theoretical understanding has been underpinned, the same remains far from being well resolved.…”

Section: Introductionmentioning

confidence: 99%

“…2019), as well as property contrasts between the inner and the outer drops, may result in obvious deviations from concentricity. This, in turn, leads to simultaneous deformation and translation of the compound drop, as against the case of a concentric one that undergoes deformation without any net migration under a uniform external electric field (Baygents, Rivette & Stone 1998; Das, Dalal & Tomar 2021; Sorgentone et al. 2021).…”

Section: Introductionmentioning

confidence: 99%

Eccentricity-induced dielectrophoretic migration of a compound drop in a uniform external electric field

2023

View full text Add to dashboard Cite

Eccentric compound drops, which are ubiquitous in many naturally inspired and engineering systems, can migrate under the sole presence of a uniform electric field, unlike the case of isolated single drops. Here, we report the migration of eccentric compound drops under a uniform electric field, imposed parallel to the line of centres of the constituting drops, by developing an approximate analytical model that applies to low Reynolds number limits under negligible droplet deformation, following axisymmetric considerations. In contrast to the sole influence of the electrohydrodynamic forces that has thus far been established to be emphatic for the eccentric configuration, here we report the additional effects induced by the dielectrophoretic forces to result in decisive manipulation in the drop migration. We show that the relative velocity between the inner and outer drops, which is a function of the eccentricity itself, dictates the dynamical evolution of the eccentricity variation under the competing electrohydrodynamic and dielectrophoretic interactions. This brings out four distinct regimes of the migration characteristics of the two drops based on their relative electro-physical properties. Our results reveal that an increase in eccentricity and the size ratio of the inner and outer droplets may induce monotonic or non-monotonic variation in the drop velocities, depending on the operating regime. We show how the interplay of various properties holds the control of selectively increasing or suppressing the eccentricity with time. These findings open up various avenues of electrically manipulative motion of encapsulated fluidic phases in various applications encompassing engineering and biology.

show abstract

Electrohydrodynamic-induced interactions between droplets

Abstract: Abstract

Cited by 20 publications

References 77 publications

Electrically modulated relaxation dynamics of pre-stretched droplets post switched-off uniaxial extensional flow

Electrically modulated relaxation dynamics of pre-stretched droplets post switched-off uniaxial extensional flow

Electric-field-mediated morpho-dynamic evolution in drop–drop coalescence phenomena in the inertio-capillary regime

Eccentricity-induced dielectrophoretic migration of a compound drop in a uniform external electric field

Contact Info

Product

Resources

About