HYDRODYNAMIC CHARACTERISTICS OF ELECTRORHEOLOGICAL FLUID IN A PARALLEL DUCT FLOW

2001 ◽  
Vol 15 (06n07) ◽  
pp. 980-987
Author(s):  
K. SHIMADA ◽  
S. KAMIYAMA
Keyword(s):  
Shear Rate ◽  
Friction Coefficient ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Apparent Viscosity ◽  
Wall Friction ◽  
Hydrodynamic Characteristics ◽  
Duct Flow ◽  
Newtonian Viscosity

An experimental investigation is conducted to clarify the hydrodynamic characteristics of ERF with elastic particles of smectite in a two-dimensional parallel duct of various widths. Experimental data on pressure difference to a volumetric flow rate in a supplying D.C. electric field are measured. These data are arranged to obtain the apparent viscosit by using the integral method of rheology. From the data of apparent viscosity, the wall friction coefficient is obtained. The increment of the apparent viscosity caused by the applying electric field is a function of shear rate as well as the electric field strength and the width of the duct. However, the wall friction coefficient is not a function of elecric field strength and the width of the parallel duct, but only of shear rate. The yield stress is a function of the width of the parallel duct as well as of electric field strength. The ratio of Non-Newtonian viscosity in the apparent viscosity is varied by the intensity of the shear rate.

DIFFERENCES IN STEADY CHARACTERISTICS AND RESPONSE TIME OF ERF ON ROTATIONAL FLOW BETWEEN ROTATING DISK AND CONCENTRIC CYLINDER

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1050-1056 ◽  
Author(s):  
K. SHIMADA ◽  
H. NISHIDA ◽  
T. FUJITA
Keyword(s):  
Shear Rate ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Current Density ◽  
Rotating Disk ◽  
Settling Time ◽  
Rotational Flow ◽  
Concentric Cylinder ◽  
Constant Shear Rate

We made an experimental investigation of the steady characteristics of torque, current density, and response time of ERF on rotational flow of the disk and the concentric cylinder. We used smectite particles suspension ERF and D.C. electric field. We compared the steady shearstress, current density, and the rise and settling time of the concentric cylinder and with those of the rotating disk. Then we clarified the differences. At a larger electric field strength, the shear stress, yield stress, and apparent viscosity to a constant shear rate in the case of the rotating disk are larger than they are in the case of the rotating concentric cylinder. However, at a larger electric field strength, the current density to a constant shear rate in the case of the rotating disk is smaller than it is in the case of the rotating concentric cylinder. Rise time of torque in the case of the rotating disk is faster than it is in the case of the rotating concentric cylinder. However, rise time of current density in the case of the rotating disk is slower than it is in the case of the rotating concentric cylinder at a small electric field strength. On the other hand, the difference of settling time of torque and current density between the rotating disk and the rotating concentric cylinder is changed by the electric field strength and shear rate. The settling time of torque in the case of the rotating disk is faster than it is in the case of the rotating concentric cylinder at a large electric field strength and large shear rate. The settling time of current density in the case of the rotating disk is slower than it is in the case of rotating concentric cylinder at a small electric field strength. Based on these results, the rotating disk has an efficiency of obtained torque to given electric power greater than that of the rotating concentric cylinder.

Study on the Test System of ERF's Performance

2013 ◽  
Vol 579-580 ◽  
pp. 813-817
Author(s):  
Xin Sheng He ◽  
Peng Huang ◽  
Kai Fei ◽  
Xiao Yi Zhang ◽  
Wei Zeng Chen ◽  
...  
Keyword(s):  
Shear Stress ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Apparent Viscosity ◽  
Performance Test ◽  
Performance Testing ◽  
Test System ◽  
Relationship Of ◽  
The Relationship

Electrorheological fluid (ERF) is a new kind of smart materials, which has a great deal of market value and broad application prospects. To meet the needs of the ERFs performance testing, design and produce of the ERF's performance test system are based on the relationship of the apparent viscosity, shear stress and electric field strength. Select the NDJ-8S digital viscometer, high voltage DC power supply, liquid container, and other parts to constitute the ERFs performance test system after considering the relationship of the apparent viscosity, shear stress, shear rate and electric field strength. The system has potentials to control voltage, change velocity, change the distance between the parallel panels, and test the yield stress of the ERF, shear stress, viscosity and other parameters. The study introduces the hardware and software device, the related experiments, and obtains the relationship of the viscosity, rotational speed, voltage, and plate gap.

TRANSIENT BEHAVIOR OF THE MICROSTRUCTURE OF ELECTRORHEOLOGICAL FLUIDS IN SHEAR FLOW MODE

2001 ◽  
Vol 15 (06n07) ◽  
pp. 695-703 ◽  
Author(s):  
S. L. VIEIRA ◽  
M. NAKANO ◽  
S. HENLEY ◽  
F. E. FILISKO ◽  
L. B. POMPEO NETO ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Shear Flow ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Transient Behavior ◽  
Electrorheological Fluids ◽  
Flow Mode ◽  
Er Fluid

It was reported that under the simultaneous stimulus of an electric field and shear, the particles in an ER fluid form lamellar formations in the direction of shear (adhered to one of the electrodes) which may be responsible for the ER activity more than the strength of the chains. In this way, it would be expected that the shear stress should change consistently with the morphology of the formations. In this work we studied the effect of shearing time, electric field strength and shear rate on the shear stress. We suggest that changes on shear stress with time are due to changes of the morphology of the lamellar formations.

Electrorheological Fluid Hysteresis

Materials ◽  
2005 ◽  
Author(s):  
Young Dae Kim ◽  
Daniel De Kee
Keyword(s):  
Shear Rate ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Particle Concentration ◽  
Electrorheological Fluid ◽  
Particle Structure ◽  
Hysteresis Behavior ◽  
Precise Control ◽  
Er Fluids

Electrorheological (ER) fluids are suspensions of polarizable particles dispersed in insulating liquids. They exhibit a rapid and reversible transition from a liquid-like to a solid-like state upon the application of an electric field. The observed shear stress - shear rate hysteresis makes the precise control of the ER mechanical devices very difficult. Hysteresis behavior of TiO2 ER fluids were observed by varying particle concentration, electric field strength, maximum shear rate, and the time of hysteresis loop. In the absence of an electric field, the stress level of the up curve exceeds that of the down curve. The presence of an electric field, reverses this trend. The extent of hysteresis becomes more significant with increasing electric field strength, particle concentration, and maximum shear rate. Hysteresis behavior of TiO2 ER fluids seems to arise mainly due to the change of the particle structure during shearing. To describe the complex rheological behavior of ER fluids, a kinetic theory is presented. Model predictions show qualitative agreement with the experimental hysteresis data.

Optical Measurement of the Electric Field Strength in a Gel Insulator

2016 ◽  
Vol 136 (10) ◽  
pp. 1420-1421
Author(s):  
Yusuke Tanaka ◽  
Yuji Nagaoka ◽  
Hyeon-Gu Jeon ◽  
Masaharu Fujii ◽  
Haruo Ihori
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Optical Measurement

Effect of external magnetic field on lane formation in driven pair-ion plasmas

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Swati Baruah ◽  
U. Sarma ◽  
R. Ganesh
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Coupling Parameter ◽  
Critical Parameters ◽  
Coulomb Coupling ◽  
Lane Formation ◽  
Parameter Values

Lane formation dynamics in externally driven pair-ion plasma (PIP) particles is studied in the presence of external magnetic field using Langevin dynamics (LD) simulation. The phase diagram obtained distinguishing the no-lane and lane states is systematically determined from a study of various Coulomb coupling parameter values. A peculiar lane formation-disintegration parameter space is identified; lane formation area extended to a wide range of Coulomb coupling parameter values is observed before disappearing to a mixed phase. The different phases are identified by calculating the order parameter. This and the critical parameters are calculated directly from LD simulation. The critical electric field strength value above which the lanes are formed distinctly is obtained, and it is observed that in the presence of the external magnetic field, the PIP system requires a higher value of the electric field strength to enter into the lane formation state than that in the absence of the magnetic field. We further find out the critical value of electric field frequency beyond which the system exhibits a transition back to the disordered state and this critical frequency is found as an increasing function of the electric field strength in the presence of an external magnetic field. The movement of the lanes is also observed in a direction perpendicular to that of the applied electric and magnetic field directions, which reveals the existence of the electric field drift in the system under study. We also use an oblique force field as the external driving force, both in the presence and absence of the external magnetic field. The application of this oblique force changes the orientation of the lane structures for different applied oblique angle values.

scholarly journals Investigating the feasibility of cerebellar transcranial direct current stimulation to facilitate post-stroke overground gait performance in chronic stroke: a partial least-squares regression approach

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Dhaval Solanki ◽  
Zeynab Rezaee ◽  
Anirban Dutta ◽  
Uttama Lahiri
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Chronic Stroke ◽  
Least Squares Regression ◽  
Significance Level ◽  
Gait Performance ◽  
Wilcoxon Rank Sum Test ◽  
Gait Parameters ◽  
The Mean

Abstract Background Investigation of lobule-specific electric field effects of cerebellar transcranial direct current stimulation (ctDCS) on overground gait performance has not been performed, so this study aimed to investigate the feasibility of two lobule-specific bilateral ctDCS montages to facilitate overground walking in chronic stroke. Methods Ten chronic post-stroke male subjects participated in this repeated-measure single-blind crossover study, where we evaluated the single-session effects of two bilateral ctDCS montages that applied 2 mA via 3.14 cm2 disc electrodes for 15 min targeting (a) dentate nuclei (also, anterior and posterior lobes), and (b) lower-limb representations (lobules VIIb-IX). A two-sided Wilcoxon rank-sum test was performed at a 5% significance level on the percent normalized change measures in the overground gait performance. Partial least squares regression (PLSR) analysis was performed on the quantitative gait parameters as response variables to the mean lobular electric field strength as the predictors. Clinical assessments were performed with the Ten-Meter walk test (TMWT), Timed Up & Go (TUG), and the Berg Balance Scale based on minimal clinically important differences (MCID). Results The ctDCS montage specific effect was found significant using a two-sided Wilcoxon rank-sum test at a 5% significance level for 'Step Time Affected Leg' (p = 0.0257) and '%Stance Time Unaffected Leg' (p = 0.0376). The changes in the quantitative gait parameters were found to be correlated to the mean electric field strength in the lobules based on PLSR analysis (R2 statistic = 0.6574). Here, the mean electric field strength at the cerebellar lobules, Vermis VIIIb, Ipsi-lesional IX, Vermis IX, Ipsi-lesional X, had the most loading and were positively related to the 'Step Time Affected Leg' and '%Stance Time Unaffected Leg,' and negatively related to the '%Swing Time Unaffected Leg,' '%Single Support Time Affected Leg.' Clinical assessments found similar improvement in the TMWT (MCID: 0.10 m/s), TUG (MCID: 8 s), and BBS score (MCID: 12.5 points) for both the ctDCS montages. Conclusion Our feasibility study found an association between the lobular mean electric field strength and the changes in the quantitative gait parameters following a single ctDCS session in chronic stroke. Both the ctDCS montages improved the clinical outcome measures that should be investigated with a larger sample size for clinical validation. Trial registration: Being retrospectively registered.

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