Three dimensional numerical simulation of drops suspended in a channel under uniform electric field

2019 ◽  
Vol 78 ◽  
pp. 32-49 ◽  
Author(s):  
M. Akbari ◽  
S. Mortazavi
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Three Dimensional ◽  
Uniform Electric Field

scholarly journals Electrorheology of a dilute emulsion of surfactant-covered drops

2019 ◽  
Vol 881 ◽  
pp. 524-550 ◽  
Author(s):  
Antarip Poddar ◽  
Shubhadeep Mandal ◽  
Aditya Bandopadhyay ◽  
Suman Chakraborty
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Surface Deformation ◽  
Three Dimensional ◽  
Shear Thickening ◽  
Field Configuration ◽  
Uniform Electric Field ◽  
Surface Tension Gradient ◽  
Drop Surface ◽  
Flow Perturbation

We investigate the effects of surfactant coating on a deformable viscous drop under the combined action of shear flow and a uniform electric field. Employing a comprehensive three-dimensional approach, we analyse the non-Newtonian shearing response of the bulk emulsion in the dilute suspension regime. Our results reveal that the location of the peak surfactant accumulation on the drop surface may get shifted from the plane of shear to a plane orthogonal to it, depending on the tilt angle of the applied electric field and strength of the electrical stresses relative to their hydrodynamic counterparts. The surfactant non-uniformity creates significant alterations in the flow perturbation around the drop, triggering modulations in the bulk shear viscosity. Overall, the shear-thinning or shear-thickening behaviour of the emulsion appears to be greatly influenced by the interplay of surface charge convection and Marangoni stresses. We show that the balance between electrical and hydrodynamic stresses renders a vanishing surface tension gradient on the drop surface for some specific shear rates, rendering negligible alterations in the bulk viscosity. This critical condition largely depends on the electrical permittivity and conductivity ratios of the two fluids and orientation of the applied electric field. Also, the physical mechanisms of charge convection and surface deformation play their roles in determining this critical shear rate. As a consequence, we obtain new discriminating factors, involving electrical property ratios and the electric field configuration, which govern the same. Consequently, the surfactant-induced enhancement or attenuation of the bulk emulsion viscosity depends on the electrical conductivity and permittivity ratios. The concerned description of the drop-level flow physics and its connection to the bulk rheology of a dilute emulsion may provide a fundamental understanding of a more complex emulsion system encountered in industrial practice.

Combination of Au Dielectrophoresis Chip and Optical Tweezers for Cell Culture

2015 ◽  
Vol 656-657 ◽  
pp. 549-553
Author(s):  
Kyohei Nishimoto ◽  
Kozo Taguchi
Keyword(s):  
Electric Field ◽  
Optical Tweezers ◽  
Cell Separation ◽  
Low Cost ◽  
Three Dimensional ◽  
Uniform Electric Field ◽  
Objective Lens ◽  
Separation System ◽  
Ac Electric Field ◽  
Viable Cells

Dielectrophoresis (DEP) force will arise when an inhomogeneous AC electric field with sinusoidal wave is applied to microelectrodes. By using DEP, we could distinguish between viable and non-viable cells by their movement through a non-uniform electric field. In this paper, we propose a yeast cell separation system, which utilizes an Au DEP chip and an optical tweezers. The Au DEP chip is planar quadrupole microelectrodes, which were fabricated by Au thin-film and a box cutter. This fabrication method is low cost and simpler than previous existing methods. The tip of the optical tweezers was fabricated by dynamic chemical etching in a mixture of hydrogen fluoride and toluene. The optical tweezers has the feature of high manipulation performance. That does not require objective lens for focusing light because the tip of optical tweezers has conical shape. By using both the Au DEP chip and optical tweezers, we could obtain three-dimensional manipulation of specific cells after viability separation.

Effects of Electrode Configurations on Internal Stress Distribution of Multilayer Actuators

2003 ◽  
Vol 785 ◽  
Author(s):  
Dong-Kyun Lee ◽  
Ji-Won Choi ◽  
Deuk-Young Han ◽  
Hyun-Jai Kim ◽  
Seok-Jin Yoon
Keyword(s):  
Numerical Simulation ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Electric Field ◽  
Internal Stress ◽  
Uniform Electric Field ◽  
Multilayer Actuator ◽  
Multilayer Actuators

ABSTRACTThe internal stress distribution in multilayer actuator was analyzed by a numerical simulation. Around the edge of conventional inter-digital electrodes, the non-uniform electric field generated the stress concentration, which caused the ceramic to crack. Various electrode configurations were presented to decrease this stress concentration. Especially the float electrode type is a promising design because this can be fabricated using almost the same process as the conventional multilayer actuator, and the simulated results indicted that the float electrode type decreased the stress concentration of inter-digital type in approximately 1/3.

scholarly journals Model Equations for Three-Dimensional Nonlinear Water Waves under Tangential Electric Field

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Bo Tao
Keyword(s):  
Electric Field ◽  
Water Waves ◽  
Three Dimensional ◽  
Liquid Sheet ◽  
Capillary Waves ◽  
Uniform Electric Field ◽  
Nonlinear Water Waves ◽  
Petviashvili Equation ◽  
Model Equations ◽  
Layer Problem

We are concerned with gravity-capillary waves propagating on the surface of a three-dimensional electrified liquid sheet under a uniform electric field parallel to the undisturbed free surface. For simplicity, we make an assumption that the permittivity of the fluid is much larger than that of the upper-layer gas; hence, this two-layer problem is reduced to be a one-layer problem. In this paper, we propose model equations in the shallow-water regime based on the analysis of the Dirichlet-Neumann operator. The modified Benney-Luke equation and Kadomtsev-Petviashvili equation will be derived, and the truly three-dimensional fully localized traveling waves, which are known as “lumps” in the literature, are numerically computed in the Benney-Luke equation.

scholarly journals Numerical simulation of an uncharged droplet in a uniform electric field

2006 ◽  
Vol 64 (7-9) ◽  
pp. 562-568 ◽  
Author(s):  
Adel M. Benselama ◽  
Jean-Luc Achard ◽  
Pascale Pham
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Uniform Electric Field

Computational Studies of Droplet Dynamics in a Steady Electric Field

2012 ◽  
Author(s):  
Ye Yao ◽  
Kevin M. Beussman ◽  
Yechun Wang
Keyword(s):  
Electric Field ◽  
Digital Microfluidics ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Uniform Electric Field ◽  
Immiscible Fluid ◽  
Droplet Deformation ◽  
Droplet Dynamics ◽  
And Migration ◽  
Neutrally Buoyant

A three-dimensional spectral boundary integral algorithm has been developed to investigate the dynamics of a neutrally buoyant and initially uncharged droplet in another immiscible fluid subjected to a steady electric field. Good agreement has been found by comparing with analytical solutions and experimental results for droplets in a uniform electric field. Benefit from the fully three-dimensional algorithm that we have developed, the droplet deformation and migration induced by the nonuniform electric field created by a point charge has been investigated. We computationally predict the deformation and migration of the droplet under the influence of physical properties of the system: resistivities, permittivities and viscosities, as well as the electric capillary number. The numerical scheme developed by this study and computational results provide foundation for the computational investigation of droplet motion in digital microfluidics.

Three-dimensional analysis of the steady-state shape and small-amplitude oscillation of a bubble in uniform and non-uniform electric fields

1999 ◽  
Vol 384 ◽  
pp. 59-91 ◽  
Author(s):  
S. M. LEE ◽  
I. S. KANG
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Indirect Effect ◽  
Oscillation Frequency ◽  
Small Amplitude ◽  
Free Oscillation ◽  
Three Dimensional ◽  
Spherical Shape ◽  
Uniform Electric Field ◽  
Small Amplitude Oscillation

A three-dimensional analysis is performed to investigate the effects of an electric field on the steady deformation and small-amplitude oscillation of a bubble in dielectric liquid. To deal with a general class of electric fields, an electric field near the bubble is approximately represented by the sum of a uniform field and a linear field. Analytical results have been obtained for steady deformation and modification of oscillation frequency by using the domain perturbation method with the angular momentum operator approach.It has been found that, to the first order, the steady shape of a bubble in an arbitrary electric field can be represented by a linear combination of a finite number of spherical harmonics Yml, where 0[les ]l[les ]4 and [mid ]m[mid ][les ]l. For the oscillation about the deformed steady shape, the overall frequency modification from the value of free oscillation about a spherical shape is obtained by considering two contributions separately: (i) that due to the deformed steady shape (indirect effect), and (ii) that due to the direct effect of an electric field. Both the direct and indirect effects of an electric field split the (2l+1)-fold degenerate frequency of Yml modes, in the case of free oscillation about a spherical shape, into different frequencies that depend on m. However, when the average is taken over the (2l+1) values of m, the frequency splitting due to the indirect effect via the deformed steady shape preserves the average value, while the splitting due to the direct effect of an electric field does not.The oscillation characteristics of a bubble in a uniform electric field under the negligible compressibility assumption are compared with those of a conducting drop in a uniform electric field. For axisymmetric oscillation modes, deforming the steady shape into a prolate spheroid has the same effect of decreasing the oscillation frequency in both the drop and the bubble. However, the electric field has different effects on the oscillation about a spherical shape. The oscillation frequency increases with the increase of electric field in the case of a bubble, while it decreases in the case of a drop. This fundamental difference comes from the fact that the electric field outside the bubble exerts a suppressive surface force while the electric field outside the conducting drop exerts a pulling force on the surface.

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