Prediction and measurement of leaky dielectric drop interactions

2022 ◽  
Vol 7 (1) ◽  
Author(s):  
Jeremy I. Kach ◽  
Lynn M. Walker ◽  
Aditya S. Khair
Keyword(s):  
Leaky Dielectric

Preparation, properties, and efficient electrically induced structure formation of a leaky dielectric photoresist

RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 82450-82458 ◽  
Author(s):  
Guowei Lv ◽  
Shihu Zhang ◽  
Jinyou Shao ◽  
Hongmiao Tian ◽  
Guolong Wang ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Structure Formation ◽  
Hydrophobic Surfaces ◽  
Photoresist Film ◽  
Leaky Dielectric ◽  
Induced Structure

Electrohydrodynamic structures with hydrophobic surfaces were fabricated instantaneously at ambient temperature using a designed leaky dielectric photoresist film.

Electrically induced pattern formation in thin leaky dielectric films

2005 ◽  
Vol 17 (3) ◽  
pp. 032104 ◽  
Author(s):  
R. V. Craster ◽  
O. K. Matar
Keyword(s):  
Pattern Formation ◽  
Dielectric Films ◽  
Leaky Dielectric

scholarly journals Electrohydrodynamics of viscous drops in strong electric fields: numerical simulations

2017 ◽  
Vol 829 ◽  
pp. 127-152 ◽  
Author(s):  
Debasish Das ◽  
David Saintillan
Keyword(s):  
Numerical Simulations ◽  
Electric Fields ◽  
Small Deformation ◽  
Dielectric Liquid ◽  
Uniform Electric Field ◽  
Liquid Drops ◽  
Wide Range ◽  
Dielectric Model ◽  
Leaky Dielectric Model ◽  
Leaky Dielectric

Weakly conducting dielectric liquid drops suspended in another dielectric liquid and subject to an applied uniform electric field exhibit a wide range of dynamical behaviours contingent on field strength and material properties. These phenomena are best described by the Melcher–Taylor leaky dielectric model, which hypothesizes charge accumulation on the drop–fluid interface and prescribes a balance between charge relaxation, the jump in ohmic currents from the bulk and charge convection by the interfacial fluid flow. Most previous numerical simulations based on this model have either neglected interfacial charge convection or restricted themselves to axisymmetric drops. In this work, we develop a three-dimensional boundary element method for the complete leaky dielectric model to systematically study the deformation and dynamics of liquid drops in electric fields. The inclusion of charge convection in our simulations permits us to investigate drops in the Quincke regime, in which experiments have demonstrated a symmetry-breaking bifurcation leading to steady electrorotation. Our simulation results show excellent agreement with existing experimental data and small-deformation theories.

scholarly journals Sedimentation of a surfactant-laden drop under the influence of an electric field

2018 ◽  
Vol 849 ◽  
pp. 277-311 ◽  
Author(s):  
Antarip Poddar ◽  
Shubhadeep Mandal ◽  
Aditya Bandopadhyay ◽  
Suman Chakraborty
Keyword(s):  
Surface Tension ◽  
Electric Field ◽  
Surfactant Concentration ◽  
Perturbation Technique ◽  
Internal Flow ◽  
Dielectric Fluid ◽  
Regular Perturbation ◽  
Spherical Drop ◽  
Leaky Dielectric ◽  
Marangoni Stress

The sedimentation of a surfactant-laden deformable viscous drop acted upon by an electric field is considered theoretically. The convection of surfactants in conjunction with the combined effect of electrohydrodynamic flow and sedimentation leads to a locally varying surface tension, which subsequently alters the drop dynamics via the interplay of Marangoni, Maxwell and hydrodynamic stresses. Assuming small capillary number and small electric Reynolds number, we employ a regular perturbation technique to solve the coupled system of governing equations. It is shown that when a leaky dielectric drop is sedimenting in another leaky dielectric fluid, the Marangoni stress can oppose the electrohydrodynamic motion severely, thereby causing corresponding changes in the internal flow pattern. Such effects further result in retardation of the drop settling velocity, which would have otherwise increased due to the influence of charge convection. For non-spherical drop shapes, the effect of Marangoni stress is overcome by the ‘tip-stretching’ effect on the flow field. As a result, the drop deformation gets intensified with an increase in sensitivity of the surface tension to the local surfactant concentration. Consequently, for an oblate type of deformation the elevated drag force causes a further reduction in velocity. For similar reasons, prolate drops experience less drag and settle faster than the surfactant-free case. In addition to this, with increased sensitivity of the interfacial tension to the surfactant concentration, the asymmetric deformation about the equator gets suppressed. These findings may turn out to be of fundamental significance towards designing electrohydrodynamically actuated droplet-based microfluidic systems that are intrinsically tunable by varying the surfactant concentration.

Nonlinear electrohydrodynamics of slightly deformed oblate drops

2015 ◽  
Vol 774 ◽  
pp. 245-266 ◽  
Author(s):  
Javier A. Lanauze ◽  
Lynn M. Walker ◽  
Aditya S. Khair
Keyword(s):  
Steady State ◽  
Electric Field ◽  
Surface Charge ◽  
Time Scale ◽  
Applied Field ◽  
Major Axis ◽  
Boundary Integral ◽  
Numerical Results ◽  
Transient Deformation ◽  
Leaky Dielectric

The transient deformation of a weakly conducting (‘leaky dielectric’) drop under a uniform DC electric field is computed via an axisymmetric boundary integral method, which accounts for surface charge convection and a finite relaxation time scale over which the drop interface charges. We focus on drops that attain an ultimate oblate (major axis normal to the applied field) steady-state configuration. The computations predict that as the time scale for interfacial charging increases, a shape transition from prolate deformation (major axis parallel to the applied field) to oblate deformation occurs at intermediate times due to the slow buildup of charge at the surface of the drop. Convection of surface charge towards the equator of the drop is shown to weaken the steady-state oblate deformation. Additionally, convection results in sharp shock-like variations in surface charge density near the equator of the drop. Our numerical results are then compared with an experimental system consisting of a millimetre-sized silicone oil drop suspended in castor oil. Agreement in the transient deformation is observed between our numerical results and experimental measurements for moderate electric field strengths. This suggests that both charge relaxation and charge convection are required, in general, to quantify the time-dependent deformation of leaky dielectric drops. Importantly, accurate prediction of the observed modest deformation requires a nonlinear model. Discrepancies between our numerical calculations and experimental results arise as the field strength is increased. We believe that this is due to the observed onset of rotation and three-dimensional flow at such high electric fields in the experiments, which an axisymmetric boundary integral formulation naturally cannot capture.

Transient Electrohydrodynamic Manipulation of Particles on the Surface of a Drop

2016 ◽  
Author(s):  
Edison C. Amah ◽  
Ian S. Fischer ◽  
Pushpendra Singh
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Control Parameter ◽  
Transient Behavior ◽  
Uniform Electric Field ◽  
Electrohydrodynamic Flow ◽  
Dielectric Model ◽  
Leaky Dielectric Model ◽  
Leaky Dielectric

In our previous studies we have shown that particles adsorbed on the surface of a drop can be concentrated at its poles or equator by applying a uniform electric field. This happens even when the applied electric field is uniform; the electric field on the surface of the drop is nonuniform, and so particles adsorbed on the surface are subjected to dielectrophoretic (DEP) forces. In this study, we use leaky dielectric model to model the transient behavior of particles at low electric field frequencies. We show that the frequency of the electric field is an important control parameter that under certain conditions can be used to collect particles at the poles or the equator, and to move them from the poles to the equator. The speed with which particles move on the surface depends on the strength of the electrohydrodynamic flow which diminishes with increasing frequency.

scholarly journals Double Swing Quiescent-Current: An Experimental Detection Method of Ferroelectricity in Very Leaky Dielectric Films

2020 ◽  
Vol 97 (1) ◽  
pp. 3-6
Author(s):  
Salvador Dueñas ◽  
Helena Castán ◽  
Óscar G. Ossorio ◽  
Guillermo Vinuesa ◽  
Héctor García ◽  
...  
Keyword(s):  
Detection Method ◽  
Dielectric Films ◽  
Experimental Detection ◽  
Quiescent Current ◽  
Leaky Dielectric
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