The Wall and Multivalent Counterion Effects on the Electrostatic Force between Like-Charged Spherical Particles Confined in a Charged Pore

Adel O Sharif; Zinat Tabatabaian; W.Richard Bowen

doi:10.1006/jcis.2002.8637

The Wall and Multivalent Counterion Effects on the Electrostatic Force between Like-Charged Spherical Particles Confined in a Charged Pore

Journal of Colloid and Interface Science ◽

10.1006/jcis.2002.8637 ◽

2002 ◽

Vol 255 (1) ◽

pp. 138-144 ◽

Cited By ~ 6

Author(s):

Adel O Sharif ◽

Zinat Tabatabaian ◽

W.Richard Bowen

Keyword(s):

Electrostatic Force ◽

Spherical Particles ◽

Multivalent Counterion

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Direct Simulation of Electrorheological Suspensions

10.1115/imece2001/fed-24923 ◽

2001 ◽

Author(s):

Aijun Wang ◽

Pushpendra Singh ◽

Nadine Aubry

Keyword(s):

Electric Field ◽

Stokes Equations ◽

Hydrodynamic Force ◽

Particle System ◽

Electrostatic Force ◽

Body Motion ◽

Three Dimensions ◽

Spherical Particles ◽

Point Dipole ◽

Direct Simulation

Abstract A new distributed multiplier/fictitious (DLM) domain method is developed for direct simulation of electrorheological (ER) suspensions subjected to spatially uniform electrical fields. The method is implemented both in two and three dimensions. The fluid-particle system is treated implicitly using the combined weak formulation described in [1,2]. The governing Navier-Stokes equations for the fluid are solved everywhere, including the interior of the particles. The flow inside the particles is forced to be a rigid body motion by a distribution of Lagrange multipliers. The electrostatic force acting on the polarized spherical particles is modeled based on the point-dipole approximation. Using our code we have studied the time evolution of particle-scale structures of ER suspensions in channels subjected to the pressure driven flow. In our study, the flow direction is perpendicular to that of the electric field. Simulations show that when the hydrodynamic force is zero, or very small compared to the electrostatic force, the particles form chains that are aligned approximately parallel to the direction of electric field. But, when the magnitude of hydrodynamic force is comparable to that of the electrostatic force the particle chains orient at an angle with the direction of the electric field. The angle between the particle chain and the direction of the electric field depends on the relative strengths of the hydrodynamic and electrostatic forces.

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The effect of many-body interactions on the electrostatic force in an array of spherical particles

Journal of Colloid and Interface Science ◽

10.1016/j.jcis.2010.01.053 ◽

2010 ◽

Vol 346 (1) ◽

pp. 232-235 ◽

Cited By ~ 1

Author(s):

Ghassan F. Hassan ◽

Adel O. Sharif ◽

Ugur Tuzun ◽

Andy Tate

Keyword(s):

Electrostatic Force ◽

Spherical Particles ◽

Many Body ◽

Many Body Interactions

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Electrostatic Force between Two Dielectric Particles in Electrorheological Fluids: beyond Spherical Particles

MATEC Web of Conferences ◽

10.1051/matecconf/201818704001 ◽

2018 ◽

Vol 187 ◽

pp. 04001 ◽

Cited By ~ 1

Author(s):

Hongzhe Tang ◽

Li Gan ◽

Wei An

Keyword(s):

Yield Stress ◽

Numerical Solutions ◽

Electrostatic Force ◽

Electrorheological Fluids ◽

Spherical Particles ◽

Image Method ◽

Dielectric Polarization ◽

Shear Yield Stress ◽

Spherical Form ◽

Shear Yield

In an effort to increase the shear yield stress of dielectric electrorheological fluids, we focus on the electrostatic force of different forms of particles in a dielectric polarization model. By solving Laplace‘s equation and applying the multiple image method and the finite element method, the analytical and numerical solutions of the electrostatic force of a two-sphere structure have been studied. The results suggest that when the dielectric mismatch factor is large and when the positions of the two spheres are nearly in contact with each other, most of the analytical solutions either over-or underestimate the force. Additionally, the structure of particles beyond the spherical form is considered. Three example cases are studied to shed light on how different geometries of particles may affect the electrostatic force, thereby influencing the shear yield stress of the fluid.

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STEM Study of Surface Plasmon Excitation in Small Spherical Particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133801 ◽

1990 ◽

Vol 48 (2) ◽

pp. 42-43

Author(s):

Daniel UGARTE

Keyword(s):

Energy Loss ◽

Spherical Particles ◽

Small Particles ◽

Bulk Materials ◽

Low Loss ◽

Plasmon Excitation ◽

Surface Modes ◽

Surface Plasmon Excitation ◽

Analytical Electron ◽

Analytical Electron Microscope

Small particles exhibit chemical and physical behaviors substantially different from bulk materials. This is due to the fact that boundary conditions can induce specific constraints on the observed properties. As an example, energy loss experiments carried out in an analytical electron microscope, constitute a powerful technique to investigate the excitation of collective surface modes (plasmons), which are modified in a limited size medium. In this work a STEM VG HB501 has been used to study the low energy loss spectrum (1-40 eV) of silicon spherical particles [1], and the spatial localization of the different modes has been analyzed through digitally acquired energy filtered images. This material and its oxides have been extensively studied and are very well characterized, because of their applications in microelectronics. These particles are thus ideal objects to test the validity of theories developed up to now.Typical EELS spectra in the low loss region are shown in fig. 2 and energy filtered images for the main spectral features in fig. 3.

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