scholarly journals Numerical simulations of residual stress and inhomogeneous conductivity effects in CNT-filled resins cured by electric field

2016 ◽  
Vol 10 (1) ◽  
pp. 15-24
Author(s):  
R. Matsuzaki ◽  
S. Hatori
Keyword(s):  
Residual Stress ◽  
Electric Field ◽  
Numerical Simulations ◽  
Inhomogeneous Conductivity

Numerical Simulations of Electric Field Driven Self-Assembly of Monolayers of Mixtures of Nanoparticles

2017 ◽  
Author(s):  
E. Amah ◽  
N. Musunuri ◽  
Ian S. Fischer ◽  
Pushpendra Singh
Keyword(s):  
Electric Field ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Self Assembly ◽  
Composite Particle ◽  
Critical Value ◽  
Direct Numerical Simulations ◽  
Composite Particles ◽  
Liquid Interfaces ◽  
Induced Dipole

We numerically study the process of self-assembly of particle mixtures on fluid-liquid interfaces when an electric field is applied in the direction normal to the interface. The force law for the dependence of the electric field induced dipole-dipole and capillary forces on the distance between the particles and their physical properties obtained in an earlier study by performing direct numerical simulations is used for conducting simulations. The inter-particle forces cause mixtures of nanoparticles to self-assemble into molecular-like hierarchical arrangements consisting of composite particles which are organized in a pattern. However, there is a critical electric intensity value below which particles move under the influence of Brownian forces and do not self-assemble. Above the critical value, when the particles sizes differed by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles forming a ring around it. Approximately same sized particles, when their concentrations are approximately equal, form binary particles or chains (analogous to polymeric molecules) in which positively and negatively polarized particles alternate, but when their concentrations differ the particles whose concentration is larger form rings around the particles with smaller concentration.

Electrokinetic instability due to streamwise conductivity gradients in microchip electrophoresis

2021 ◽  
Vol 925 ◽  
Author(s):  
Kaushlendra Dubey ◽  
Sanjeev Sanghi ◽  
Amit Gupta ◽  
Supreet Singh Bahga
Keyword(s):  
Electric Field ◽  
Numerical Simulations ◽  
Electric Fields ◽  
Quantitative Measure ◽  
Underlying Mechanism ◽  
Scaling Analysis ◽  
Recirculating Flow ◽  
Electrokinetic Instability ◽  
Spatial Features ◽  
Proper Orthogonal Decomposition Technique

We present an experimental and numerical investigation of electrokinetic instability (EKI) in microchannel flow with streamwise conductivity gradients, such as those observed during sample stacking in capillary electrophoresis. A plug of a low-conductivity electrolyte solution is initially sandwiched between two high-conductivity zones in a microchannel. This spatial conductivity gradient is subjected to an external electric field applied along the microchannel axis, and for sufficiently strong electric fields an instability sets in. We have explored the physics of this EKI through experiments and numerical simulations, and supplemented the results using scaling analysis. We performed EKI experiments at different electric field values and visualised the flow using a passive fluorescent tracer. The experimental data were analysed using the proper orthogonal decomposition technique to obtain a quantitative measure of the threshold electric field for the onset of instability, along with the corresponding coherent structures. To elucidate the physical mechanism underlying the instability, we performed high-resolution numerical simulations of ion transport coupled with fluid flow driven by the electric body force. Simulations reveal that the non-uniform electroosmotic flow due to axially varying conductivity field causes a recirculating flow within the low-conductivity region, and creates a new configuration wherein the local conductivity gradients are orthogonal to the applied electric field. This configuration leads to EKI above a threshold electric field. The spatial features of the instability predicted by the simulations and the threshold electric field are in good agreement with the experimental observations and provide useful insight into the underlying mechanism of instability.

scholarly journals A Liquid-Metal-Based Dielectrophoretic Microdroplet Generator

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 769 ◽  
Author(s):  
Wang ◽  
Zhang ◽  
Gao ◽  
Wang ◽  
Deng ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Electric Field ◽  
Numerical Simulations ◽  
Parametric Study ◽  
Microfluidic Channel ◽  
Droplet Generator ◽  
Metal Electrodes ◽  
Droplet Generators

This paper proposes a novel microdroplet generator based on the dielectrophoretic (DEP) force. Unlike the conventional continuous microfluidic droplet generator, this droplet generator is more like “invisible electric scissors”. It can cut the droplet off from the fluid matrix and modify droplets’ length precisely by controlling the electrodes’ length and position. These electrodes are made of liquid metal by injection. By applying a certain voltage on the liquid-metal electrodes, the electrodes generate an uneven electric field inside the main microfluidic channel. Then, the uneven electric field generates DEP force inside the fluid. The DEP force shears off part from the main matrix, in order to generate droplets. To reveal the mechanism, numerical simulations were performed to analyze the DEP force. A detailed experimental parametric study was also performed. Unlike the traditional droplet generators, the main separating force of this work is DEP force only, which can produce one droplet at a time in a more precise way.

Residual stress near single shot peening impingements determined by nanoindentation and numerical simulations

2014 ◽  
Vol 50 (5) ◽  
pp. 2284-2297 ◽  
Author(s):  
P. Mann ◽  
H. Y. Miao ◽  
A. Gariépy ◽  
M. Lévesque ◽  
R. R. Chromik
Keyword(s):  
Residual Stress ◽  
Numerical Simulations ◽  
Shot Peening ◽  
Single Shot

Numerical Simulations of Capillary Electrokinetic Pinched Injection Separation Flows in Microchannels

2004 ◽  
Author(s):  
Bakhtier Farouk ◽  
Fang Yan
Keyword(s):  
Electric Field ◽  
Numerical Simulations ◽  
Separation Performance ◽  
Species Concentration ◽  
Separation Channel ◽  
Electrokinetic Flow ◽  
Step Flow ◽  
Optimal Separation ◽  
Separation Flows ◽  
Separation Performances

Numerical simulations were performed to study the capillary electrokinetic flow in microchannels. A sample stream consisting of three different species is focused during the loading step and driven into a separation channel during the dispensing step. Flow fields and species distributions are simulated for both the loading and the dispensing steps in a two dimensional cross channel device. The evolution of each sample species concentration at the end of the separation channel is predicted. The separation resolution is defined from the sample species concentration band retention time and band width. Different separation performances can be obtained by manipulating the electric field strengths. A series of simulations for different electric field distributions and field magnitudes in the channel are presented. The goal of these simulations is to identify the parameters providing optimal separation performance. The effect of both loading and dispensing schemes on species concentration and separation resolution is presented.

The effect of uniform electric field on the cross-stream migration of a drop in plane Poiseuille flow

2016 ◽  
Vol 809 ◽  
pp. 726-774 ◽  
Author(s):  
Shubhadeep Mandal ◽  
Aditya Bandopadhyay ◽  
Suman Chakraborty
Keyword(s):  
Steady State ◽  
Electric Field ◽  
Numerical Simulations ◽  
Poiseuille Flow ◽  
Shape Deformation ◽  
Uniform Electric Field ◽  
Plane Poiseuille Flow ◽  
Stream Migration ◽  
The Cross ◽  
Transverse Position

The effect of a uniform electric field on the motion of a drop in an unbounded plane Poiseuille flow is studied analytically. The drop and suspending media are considered to be Newtonian and leaky dielectric. We solve for the two-way coupled electric and flow fields analytically by using a double asymptotic expansion for small charge convection and small shape deformation. We obtain two important mechanisms of cross-stream migration of the drop: (i) shape deformation and (ii) charge convection. The second one is a new source of cross-stream migration of the drop in plane Poiseuille flow which is due to an asymmetric charge distribution on the drop surface. Our study reveals that charge convection can cause a spherical non-deformable drop to migrate in the cross-stream direction. The combined effect of charge convection and shape deformation significantly alters the drop velocity, drop trajectory and steady state transverse position of the drop. We predict that, depending on the orientation of the applied uniform electric field and the relevant drop/medium electrohydrodynamic parameters, the drop may migrate either towards the centreline of the flow or away from it. We obtain that the final steady state transverse position of the drop is independent of its initial transverse position in the flow field. Most interestingly, we show that the drop can settle in an off-centreline steady state transverse position. Two-dimensional numerical simulations are also performed to study the drop motion in the combined presence of plane Poiseuille flow and a tilted electric field. The drop trajectory and steady state transverse position of the drop obtained from numerical simulations are in qualitative agreement with the analytical results.

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