Electrorheology

MRS Bulletin ◽  
1991 ◽  
Vol 16 (8) ◽  
pp. 38-43 ◽  
Author(s):  
Therese C. Jordan ◽  
Montgomery T. Shaw
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
High Speed ◽  
Flow Properties ◽  
Electric Field Effects ◽  
Properties Of Materials ◽  
Strong Electric Fields ◽  
Silica Suspensions ◽  
Type Of Behavior ◽  
Damping Systems

The influence of electric fields on the deformation and flow properties of materials has been a subject of interest for many years. Recently, there has been renewed interest in a particular branch of these electric field effects—the electrorheological (ER) effect. The ER effect is also known as the Winslow effect after its founder Willis Winslow. Winslow observed that applying strong electric fields to nonaqueous silica suspensions activated with a small amount of water caused rapid solidification of the originally fluid material. This type of behavior was seen as instrumental in the development of high-speed valves, reactive damping systems, and a host of other applications.

Effect of a High Electric Field on the Thermal and Phase Change Characteristics of an Impacting Drop

2019 ◽  
Author(s):  
Abhishek Basavanna ◽  
Prajakta Khapekar ◽  
Navdeep Singh Dhillon
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Phase Change ◽  
Electric Fields ◽  
High Speed ◽  
Impact Behavior ◽  
Liquid Drops ◽  
Active Interest ◽  
Post Impact ◽  
High Electric Fields

Abstract The effect of applied electric fields on the behavior of liquids and their interaction with solid surfaces has been a topic of active interest for many decades. This has important implications in phase change heat transfer processes such as evaporation, boiling, and condensation. Although the effect of low to moderate voltages has been studied, there is a need to explore the interaction of high electric fields with liquid drops and bubbles, and their effect on heat transfer and phase change. In this study, we employ a high speed optical camera to study the dynamics of a liquid drop impacting a hot substrate under the application of high electric fields. Experimental results indicate a significant change in the pre- and post-impact behavior of the drop. Prior to impact, the applied electric field elongates the drop in the direction of the electric field. Post-impact, the recoil phase of the drop is significantly affected by charging effects. Further, a significant amount of micro-droplet ejection is observed with an increase in the applied voltage.

Electric Field Effects on the Stability of Vapor Microlayers: Enhancement of Heat Transfer

Materials ◽  
2003 ◽  
Author(s):  
Subramanian Sankaran ◽  
Jeffrey S. Allen ◽  
Leonard Gumennik
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heat Fluxes ◽  
Enhancement Of Heat Transfer ◽  
Electric Field Effects ◽  
Heater Wire ◽  
Experimental Parameters ◽  
Flux Level ◽  
The Stability ◽  
The Relationship

The effect of dc electric fields on destabilization of a vapor microlayer formed during film boiling at various subcooling levels is investigated. High voltage electric fields up to 2000 volts were applied between a 127 μm heater wire and a screen electrode that is concentrically placed at a radius of 25 mm. The qmax and qmin heat fluxes were also measured for the various subcooling and electric field strengths. Up to 50% increase in the qmax and the qmin heat fluxes were observed when using the electric fields in this range of experimental parameters. The relationship among subcooling level for a given fluid, the heat flux level, and the electric field strength required to reach the qmin condition is of interest. The preliminary experimental results and the bubble departure and transition boiling patterns resulting from destabilization of the vapor microlayer are discussed.

Investigation of the electroplastic effect using optical and conventional techniques

1995 ◽  
Vol 10 (2) ◽  
pp. 258-260 ◽  
Author(s):  
C.T. Stanton ◽  
C.S. Coffey ◽  
F. Zerilli
Keyword(s):  
Electric Field ◽  
Plastic Flow ◽  
Applied Electric Field ◽  
Alkali Halide ◽  
Optical Methods ◽  
Flow Properties ◽  
Electroplastic Effect ◽  
Preliminary Results ◽  
Properties Of Materials ◽  
Alkali Halide Crystals

The electroplastic effect in materials is an interesting and potentially useful phenomenon in which an applied electric field affects the plastic flow properties of materials under strain. We have undertaken a study to use optical methods to monitor changes in alkali halide crystals undergoing the electroplastic effect. Some preliminary results from this work are presented along with more conventional quasi-static measurements of the electroplastic effect.

scholarly journals Solar and geomagnetic activity effects on mid-latitude F-region electric fields

2008 ◽  
Vol 26 (9) ◽  
pp. 2911-2921 ◽  
Author(s):  
V. V. Kumar ◽  
M. L. Parkinson ◽  
P. L. Dyson ◽  
R. Polglase
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Geomagnetic Activity ◽  
High Speed ◽  
Theoretical Models ◽  
Solar Flux ◽  
Quiet Time ◽  
F Region ◽  
Diurnal Patterns ◽  
Ae Index

Abstract. Diurnal patterns of average F-region ionospheric drift (electric field) and their dependence on solar and geomagnetic activity have been defined using digital ionosonde Doppler measurements recorded at a southern mid-latitude station (Bundoora 145.1° E, 37.7° S geographic, 49° S magnetic). A unique database consisting of 300 907 drift velocities was compiled, mostly using one specific mode of operation throughout 1632 days of a 5-year interval (1999–2003). The velocity magnitudes were generally larger during the night than day, except during the winter months (June–August), when daytime velocities were enhanced. Of all years, the largest drifts tended to occur during the high speed solar wind streams of 2003. Diurnal patterns in the average quiet time (AE<75 nT) meridional drifts (zonal electric field) peaked at up to ~6 m s−1 poleward (0.3 mV m−1 eastward) at 03:30 LST, reversing in direction at ~08:30 LST, and gradually reaching ~10 m s−1 equatorward at ~13:30 LST. The quiet time zonal drifts (meridional electric fields) displayed a clear diurnal pattern with peak eastward flows of ~10 m s−1 (0.52 mV m−1 equatorward) at 09:30 LST and peak westward flows around midnight of ~18 m s−1 (0.95 mV m−1 poleward). As the AE index increased, the westward drifts increased in amplitude and they extended over a greater fraction of the day. The perturbation drifts changed in a similar way with decreasing Dst except the daytime equatorward flows strengthened with increasing AE index, whereas they became weak for Dst<−60 nT. The responses in all velocity components to changing solar flux values were small, but net poleward perturbations during the day were associated with large solar flux values (>192×10−22 W m−2 Hz−1). These results help to more fully quantify the response of the mid-latitude ionosphere to changing solar and geomagnetic conditions, as required to refine empirical and theoretical models of mid-latitude electric fields.

Comparison of Cable Insulation Control in Weak and Strong Electric Fields

2015 ◽  
Vol 756 ◽  
pp. 486-490 ◽  
Author(s):  
Nadezda S. Starikova ◽  
Vitaly V. Redko ◽  
G.V. Vavilova
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Strong Electric Field ◽  
Weak Electric Field ◽  
Cable Insulation ◽  
Modern Methods ◽  
Insulation Thickness ◽  
Defect Dimension ◽  
Cylindrical Capacitor ◽  
Strong Electric Fields

In this paper the modern methods of cable products insulation control are referred. A comparison of efficiency of the cable insulation defects control by changing in cable area capacitance is carried out in the strong and weak electric fields. The electric cable can be represented as a cylindrical capacitor, but to simplify the issue the insulation area is represented as a plate capacitor with anisotropic dielectric. The cable insulation model is created in the software Comsol Multyphysic. The effect of the defect dimension on the cable area electric capacitance in a strong and weak electric field is described. Also, the control sensitivity of both methods was assessed and compared with each other. The control sensitivity in a weak electric field is slightly higher for the defects with small size (less than 70% from insulation thickness). The control sensitivity in a strong electric field is considerably higher for the defects with big size (more than 70% from insulation thickness).

High-Speed Separation of Linear and Supercoiled DNA by Capillary Electrophoresis. Buffer, Entangling Polymer, and Electric Field Effects

1998 ◽  
Vol 70 (3) ◽  
pp. 574-579 ◽  
Author(s):  
Hidehiro Oana ◽  
Richard W. Hammond ◽  
Jeffrey J. Schwinefus ◽  
Shau-Chun Wang ◽  
Masao Doi ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Electric Field ◽  
High Speed ◽  
Supercoiled Dna ◽  
Electric Field Effects ◽  
Field Effects

Calculation of the transverse conductivity for electrons interacting with waves in strong electric fields

1968 ◽  
Vol 46 (23) ◽  
pp. 2659-2661 ◽  
Author(s):  
Harold N. Spector
Keyword(s):  
Distribution Function ◽  
Electric Field ◽  
Electric Fields ◽  
Optical Lattice ◽  
Transverse Electric ◽  
Lattice Vibrations ◽  
Transverse Electric Fields ◽  
Transverse Conductivity ◽  
Strong Electric Fields ◽  
The Waves

We have obtained the transverse a.c. conductivity for electrons interacting with waves in the presence of strong d.c. electric fields. The presence of the d.c. electric field leads to the introduction of a drifted distribution function for the electrons and a complex, field-dependent temperature. The expression for the transverse a.c. conductivity can be used to find the effects of the electric field on the propagation and absorption of waves in solids which induce transverse electric fields. We have applied our results to the interaction of electrons with transverse optical lattice vibrations and find that for all values of ql, it is the drifted distribution function which leads to the amplification of the waves.

Electrohydrodynamics of Drops and Vesicles

2019 ◽  
Vol 51 (1) ◽  
pp. 305-330 ◽  
Author(s):  
Petia M. Vlahovska
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Lipid Membranes ◽  
Uniform Electric Field ◽  
Dielectric Fluids ◽  
Weakly Conducting ◽  
Strong Electric Fields ◽  
Leaky Dielectric ◽  
Quincke Rotation ◽  
Experimental And Theoretical Studies

The 1969 review by J.R. Melcher and G.I. Taylor defined the field of electrohydrodynamics. Fifty years on, the interaction of weakly conducting (leaky dielectric) fluids with electric fields continues to yield intriguing phenomena. The prototypical system of a drop in a uniform electric field has revealed remarkable dynamics in strong electric fields such as symmetry-breaking instabilities (e.g., Quincke rotation) and streaming from the drop equator. This review summarizes recent experimental and theoretical studies in the area of fluid particles (drop and vesicles) in electric fields, with a focus on the transient dynamics and extreme deformations. A theoretical framework to treat the time evolution of nearly spherical shapes is provided. The model has been successful in describing the dynamics of vesicles (closed lipid membranes) in an electric field, highlighting the broader range of applicability of the leaky dielectric approach.

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