OSCILLATORY SQUEEZE FLOW OF ELECTRORHEOLOGICAL FLUID WITH TRANSITIONAL ELECTRIC FIELD

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1249-1255 ◽  
Author(s):  
JIE PENG ◽  
KE-QIN ZHU
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Phase Difference ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Electrorheological Fluid ◽  
Squeeze Flow ◽  
Field Frequency ◽  
Er Fluid ◽  
Oscillatory Squeeze Flow

The oscillatory squeeze flow of electrorheological (ER) fluid between two parallel discal electrode with transitional electric field is studied numerically in this paper. The ER fluid is modeled as Bingham-like fluid with the continuous modification model proposed by Papanastasiou. The numerical solutions based on the Navier-Stokes equations are presented by using the finite volume methods on the deforming grid. The force transmitted across the fluid under dc and ac electric fields are calculated. The effects of the electric field frequency and the phase difference between the ac electric field and mechanical oscillation are studied. The magnitude and the shape of the transmitted forces is shown to be not only a function of the applied voltage and the mechanical frequency but also the phase difference.

scholarly journals Internal Damper Characteristics of Rotor System with Submerged ER Fluid Journal Bearing

1997 ◽  
Vol 3 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Siyoul Jang ◽  
John A. Tichy
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Shear Strain ◽  
Yield Stress ◽  
Electric Fields ◽  
Journal Bearing ◽  
Shear Strain Rate ◽  
Newtonian Flow ◽  
Damping Coefficients ◽  
Er Fluid

Electro-Rheological (ER) fluid behavior is similar to Bingham fluid’ s. Only when the shear stress magnitude of ER fluid exceeds the yield stress, Newtonian flow results. Continuous shear strain rate equation about shear stress which simulates Bingham-like fluid shows viscosity variations. Shear yield stress is controlled by electric fields. Electric fields in circumferential direction around the journal are also changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds' equation for submerged journal bearing. Fluid film pressure and perturbation pressures are solved using switch function of Elord's algorithm for cavitation boundary condition. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor-bearing system is computed. It is found that there are no big differences in load capacities with the selected electric field parameters at low eccentric region and higher electric field can support more load with stability at low eccentric region.

Electrorheological Fluids in Squeeze under AC and DC Excitation

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1861-1869 ◽  
Author(s):  
J. L. Sproston ◽  
A. K. El Wahed ◽  
R. Stanway
Keyword(s):  
Excitation Frequency ◽  
Rheological Behaviour ◽  
Electrorheological Fluids ◽  
Squeeze Flow ◽  
Dc Excitation ◽  
Rate Characteristic ◽  
Input Waveform ◽  
Comparison Of The Results ◽  
Er Fluid ◽  
Oscillatory Squeeze Flow

This paper is concerned with an experimental investigation of the performance of an ER fluid in oscillatory squeeze-flow and a comparison of the results with those predicted by a quasi-steady theoretical model in which the rheological behaviour of the fluid is assumed to follow a bi-viscous shears stress/shear rate characteristic. The fluid is sandwiched between two parallel plane electrodes, the upper one stationary and the lower one oscillating normal to its plane. Of particular interest is the temporal variation in the force transmitted through the fluid in response to changes in the oscillation frequency and amplitude and the level of applied AC and DC voltages. The magnitude of the transmitted forces in the AC case is seen to be not only a function of the applied voltage but also of the shape of the input waveform and the electrical excitation frequency. In all cases these forces are found to be smaller than those seen in the corresponding DC case.

Performance Evaluation of Electro-Rheological Fluid and Its Applications to Micro-Parts Fine-Machining

2006 ◽  
Vol 315-316 ◽  
pp. 352-356
Author(s):  
Qiu Sheng Yan ◽  
F.F. Bi ◽  
N.Q. Wu
Keyword(s):  
Performance Evaluation ◽  
Electric Field ◽  
Electrorheological Fluid ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Aspheric Surface ◽  
Surface Machining ◽  
Abrasive Particles ◽  
Micro Parts ◽  
Er Fluid

This article first presents the performance of Electrorheological Fluid (ER fluid). Thus, a new-style machining technique based on ER effect to form a tiny grinding wheel is developed for superfine machining. By adding abrasive particles to ER, an array of stable chains of ER particles can be shaped when an electric field is applied and abrasive particles are fixed to these chains structure. When the tip of tool is rotated, the abrasive particles rotate with the flow and a superfine grinding process come into being. This process is expected to be applicable to the aspheric surface machining of micro miniature components made of optic glass or other hard-brittle materials.

Properties and Structure of Ni/TiO2/Polar Molecule Core-Shell Particles Electrorheological Fluid

2012 ◽  
Vol 512-515 ◽  
pp. 2166-2170
Author(s):  
Suo Kui Tan ◽  
Xiao Ping Song ◽  
Hong Zhao ◽  
Song Ji ◽  
Li Qiao ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electrorheological Fluid ◽  
Polar Molecule ◽  
Fluid Properties ◽  
Structure Observation ◽  
Shell Particles ◽  
The Relationship ◽  
Er Fluid

By means of mechanical properties test and structure observation， the relationship among electric field strength, polar molecule type, content on the Ni/TiO2group electrorheological fluid properties have been analyzed. It is found that with increasing electric field strength，the properties of electrorheological fluid increased for same composition ER fluid. Different type polar molecules have distinct effect. For same particle，with increasing polar molecule content，the property is increased, but there is a critical value . Polar molecule make particles chain of electrorheological fluid become strong，coarse and interweaved each other.

Study on Material Removal in Electrorheological Fluid-Assisted Polishing

2011 ◽  
Vol 314-316 ◽  
pp. 1131-1134
Author(s):  
Lei Zhang ◽  
Yun Wei Zhao ◽  
Zhuo Yang
Keyword(s):  
Electric Field ◽  
Material Removal ◽  
Electrorheological Fluid ◽  
Experimental Results ◽  
Abrasive Particles ◽  
Conductive Materials ◽  
Diamond Particles ◽  
Theoretical Predictions ◽  
Polishing Fluid ◽  
Er Fluid

The material removal is investigated in electrorheological (ER) fluid-assisted polishing of conductive materials. The combination structure of ER particles with abrasive particles in ER polishing fluid is discussed when the electric field is applied. The forces exerted on the abrasive particles for material removal are analyzed. According to Preston’s equation, a model for material removal of the polished conductive workpiece is derived. Polishing experiments with diamond particles for WC is conducted and the experimental results are compared with the theoretical predictions, which confirm the validity of the presented model.

The Effect of Electrostatic Forces on the Distribution of Drops in a Channel

2002 ◽  
Author(s):  
Arturo Ferna´ndez ◽  
Jiacai Lu ◽  
Asghar Esmaeeli ◽  
Gre´tar Tryggvason
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Hydrodynamic Interaction ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Dielectric Fluids ◽  
Wide Range ◽  
Leaky Dielectric Model

Direct numerical simulations are used to examine the effect of electric fields on the behavior of suspension of drops in dielectric fluids. The effect of electric field is modeled using the “leaky dielectric” model, coupled with the full Navier-Stokes equations. The governing equations are solved using a front-tracking/finite volume technique. The interaction of the drops is strongly dependant on the conductivity and the permittivity ratio, but fibration, where drops line up into long columns, takes place over a wide range of these parameters. The hydrodynamic interaction due to fluid circulation induced by the electric field has a strong influence on the drop distribution and the rate of fibration.

Investigation into Electrorheological Fluid-Assisted Polishing Optical Glass

2011 ◽  
Vol 110-116 ◽  
pp. 1099-1106
Author(s):  
Yun Wei Zhao ◽  
De Xu Geng ◽  
Xiao Min Iu ◽  
Jin Tao Zhang
Keyword(s):  
Electric Field ◽  
Silicone Oil ◽  
Optical Glass ◽  
Electrorheological Fluid ◽  
Abrasive Particles ◽  
Micro Tool ◽  
Ultra Precision ◽  
Aspherical Lenses ◽  
Field Lines ◽  
Er Fluid

Electrorheological (ER) fluid-assisted polishing process is the ultra precision finishing technologies for micro-aspherical lenses and dies. The principle of ER fluid-assisted polishing (ERP) is to use ER effect as a result of the application of electric field. The ER particles and abrasive particles suspended in silicone oil are polarized in which ER particles strongly attract each other and aggregate into chain like structure along the electric field lines, and the abrasive particles may adhere to the ER chain. The force acting on ER particles and abrasive particles in an electric field is calculated. Furthermore, experiments of polishing optical glass with Al2O3 are carried out to find the influential regularities of polishing time, rotational speed of micro-tool, voltage, the density of abrasives in ER fluid on the surface roughness.

Electrical Tomography Sensing and Dielectrophoresis in Microchannel for 3D Particle Mixing

2011 ◽  
Author(s):  
Nur Tantiyani Ali Othman ◽  
Je-Eun Choi ◽  
Masahiro Takei
Keyword(s):  
Electric Field ◽  
Cross Section ◽  
Electric Fields ◽  
Cross Sections ◽  
Electrical Tomography ◽  
Field Frequency ◽  
Particle Mixing ◽  
Measurement Plane ◽  
Electric Field Frequency ◽  
The Relationship

The present study describes the electrical tomography sensing and dielectrophoresis (DEP) force for visualize the 3D particle mixing in the microchannel system. In the presence of non-uniform electric fields generated by point microelectrodes, the dynamic distribution behaviors of a polystyrene particle and deionized water had been investigated in this system. Microchannel was fabricated with five cross sections where 12 electrodes were installed for each measurement plane. In this experiment, the relationship between electric field frequency and DEP force of particles are calculated at different electric frequencies and diameter of particles. The applied electric field intensities are E = ±1 V/mm, ±3 V/mm and ±5 V/mm while the electric field frequencies are f = 1 kHz, 10 kHz, 100 kHz and 1 MHz and the diameter of particles are 1.3μm, 1.5μm and 2.0μm are investigated in this experiment. Simultaneously, imaged by manipulating tomography sensing at cross section A, C and D and the coupled DEP forces at cross section B and D, the particles flowing had been visualized and concentrate uniformly at near the outlets. The electrical capacitances and DEP forces between the electrode pairs of the microchannel were measured and the ECT tomograms representing the particle distribution were constructed from the measured capacitance data for each cross section in microchannel.

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