Dynamics of Thin Liquid Bilayers Subjected to an External Electric Field

2014 ◽  
Author(s):  
Hadi Nazaripoor ◽  
Charles R. Koch ◽  
Subir Bhattacharjee
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Electrostatic Force ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Structure Evolution ◽  
Time Step ◽  
Spatial Dimensions ◽  
Thin Film Equation ◽  
Adaptive Time Step

Spatiotemporal evolution of liquid-liquid interface leading to dewetting and pattern formation is investigated for thin liquid bilayeres subjected to the long range electrostatic force and the short range van der Waals forces. Based on the 2D weakly non-linear thin film equation three dimensional structure evolution is numerically simulated. A combined finite difference for the spatial dimensions and an adaptive time step ODE solver is used to solve the governing equation. For initially non-wetting surfaces, the stabilizing effects of viscosity and interfacial tension and the destabilizing effect of the Hamaker constant are investigated. Electrostatic interaction is calculated analytically for both perfect dielectric-perfect dielectric and ionic conductive-perfect dielectric bilayers. Ionic conductive-perfect dielectric bilayers based on the electric permittivity ratio of layers are found to be stabilized or deformed in response to the applied external electric field.

Electrostatic Forces on Particles Floating Within the Interface Between Two Immiscible Fluids

2007 ◽  
Author(s):  
Nadine Aubry ◽  
Pushpendra Singh
Keyword(s):  
Dielectric Properties ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
External Electric Field ◽  
Capillary Force ◽  
Electrostatic Force ◽  
Immiscible Fluids ◽  
Electrostatic Forces ◽  
Dipole Interactions

The objective of this paper is to study the dependence of the electrostatic force that act on a particle within the interface between two immiscible fluids on the parameters such as the dielectric properties of the fluids and particles, the particle’s position within the interface, and the electric field strength. It is shown that the component of electrostatic force normal to the interface varies as a2, where a is the particle radius, and since in equilibrium it is balanced by the vertical capillary force, the interfacial deformation caused by the particle changes when an external electric field is applied. In addition, there are lateral electrostatic forces among the particles due to the dipole-dipole interactions which, when the distance between two particles is O(a), vary as a2, and remain significant for submicron sized particles.

A DNS Study of Falling Droplets Under Effects of Electric Field

2017 ◽  
Author(s):  
Esmaiil Ghasemisahebi ◽  
Hassan Bararnia ◽  
Soheil Soleimanikutanaei ◽  
Cheng-Xian Lin
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Open Source ◽  
External Electric Field ◽  
Three Dimensional ◽  
Numerical Results ◽  
Grid Refinement ◽  
Adaptive Grid Refinement ◽  
Side Walls ◽  
Density Ratios

In this study deformation and breakup of a falling drop which is surrounded by another liquid are modeled numerically. The drop is influenced by an external electric field which is applied uniformly on the side walls of the domain. An open-source volume-of-fluid solver, Gerris with dynamic adaptive grid refinement has been used for numerically modeling the three-dimensional deformation of a falling droplet. The numerical results are presented for various values of density ratios and electrical conductivity and permittivity. The current numerical results are compared with previous experimental and analytical works which shows a great agreement between them.

3D Numerical Analysis of Joule Heating Effect on Electroosmotic Flow in Microchannels

2006 ◽  
Author(s):  
Reza Monazami ◽  
Shahrzad Yazdi ◽  
Mahmoud A. Salehi
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Charge Distribution ◽  
Cross Section ◽  
Joule Heating ◽  
Electroosmotic Flow ◽  
Three Dimensional ◽  
Micro Channel ◽  
Heating Effect ◽  
Energy Equations

In this paper, a three-dimensional numerical model is developed to analyze the influence of the Joule heating on flow characteristics of an electroosmotic flow through square cross section micro-channels. The governing system of equations consists of three sets of equations: electric potential distribution, flow-field and energy equations. The solution procedure involves three steps. The net charge distribution on the cross section of the micro-channel is computed by solving two-dimensional Poisson-Boltzmann equation using the finite element method. Then, using the computed fluid’s charge distribution, the magnitude of the resulting body force due to interaction of an external electric field with the charged fluid elements is calculated along the micro-channel. Finally, three dimensional coupled Navier-Stokes and energy equations are solved by considering the presence of the electro-kinetic body forces and the volumetric heat generation due to Joule heating for three different external electric field strengths. The results reveal that flow patterns are significantly affected by temperature field distribution caused by Joule heating effect especially for high electric field strength cases.

3D Numerical Analysis of Velocity Profiles of PD, EO and Combined PD-EO Flows Through Microchannels

2006 ◽  
Author(s):  
Shahrzad Yazdi ◽  
Reza Monazami ◽  
Mahmoud A. Salehi
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Charge Distribution ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Ionic Concentration ◽  
Micro Channel ◽  
Micro Channels ◽  
Wide Range ◽  
Pressure Driven

In this paper, a three-dimensional numerical model is developed to analyze flow characteristics of pressure driven, electroosmotic and combined pressure driven-electroosmotic flows through micro-channels. The governing system of equations consists of the electric-field and flow-field equations. The solution procedure involves three steps. The net charge distribution on the cross section of the micro-channel is computed by solving two-dimensional Poisson-Boltzmann equation using the finite element method. Then, using the computed fluid’s charge distribution, the magnitude of the resulting body force due to interaction of an external electric field with the charged fluid is calculated along the micro-channel. Finally, three dimensional Navier-Stokes equations are solved by considering the presence of the electro-kinetic body forces in the flow system for electroosmotic and combined pressure driven electroosmotic flow cases. The results reveal that the flow patterns for combined PD-EO cases are significantly different from the parabolic velocity profile of the laminar pressure-driven flow. The effect of the liquid bulk ionic concentration and the external electric field strength on flow patterns through the square-shaped micro-channels is also investigated over a wide range of external electric field strengths and bulk ionic concentration.

Large-scale disruptions in a current-carrying magnetofluid

1986 ◽  
Vol 35 (1) ◽  
pp. 1-42 ◽  
Author(s):  
Jill P. Dahlburg ◽  
David Montgomery ◽  
Gary D. Doolen ◽  
William H. Matthaeus
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Large Scale ◽  
Magnetic Energy ◽  
Spatial Scales ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Subsequent Development ◽  
Viscous Term ◽  
Sawtooth Oscillations

A pseudo-spectral three-dimensional Strauss-equations code is used to describe internal disruptions in a strongly magnetized, electrically-conducting fluid, with and without an externally applied, axial electric field. Rigid conducting walls form a square (x, y) boundary, and periodic boundary conditions are assumed in the axial (z) direction. Typical resolution is 64 × 64 × 32 and the maximum Lundquist number is approximately 400. The dynamics are dominated by a helical current filament which wraps itself around the axis of the cylinder; parts of this filament can sometimes become strongly negative. The ratio of turbulent kinetic energy to total poloidal magnetic energy rises from very small values to values of the order of a few hundredths, and executes ‘bounces’ as a function of time in the absence of the external electric field. In the presence of the external electric field, the first bounce is by far the largest, then the plasma settles into a non-uniform quasi-steady state characterized by a poloidal fluid velocity flow. At the large scales, this flow has the shape of a pair of counter-rotating bean-shaped vortices. The subsequent development of this fluid flow depends strongly upon whether or not a viscous term is added to the equation of motion. Inclusion of viscosity tends to damp the flow and leads to pronounced subsequent bounces suggestive of sawtooth oscillations, though the first bounce remains substantially the largest. By means of a three-mode (Lorenz-like) truncation of the Strauss equations, the evolution of the largest spatial scales alone may be examined. Some time-dependent solutions of the low-order truncation system suggest qualitative agreement with fully resolved solutions of the Strauss equations, while other solutions exhibit interesting dynamical-systems behaviour which is thus far unparalleled in the fully-resolved simulation results.

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