SIMULATIONS OF ELECTRORHEOLOGICAL FLUIDS WITH HYDRODYNAMIC LUBRICATION

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3211-3217 ◽  
Author(s):  
J.R. MELROSE ◽  
S. ITOH ◽  
R.C. BALL
Keyword(s):  
Electrostatic Interactions ◽  
Hydrodynamic Lubrication ◽  
Layer Structure ◽  
Electrorheological Fluids ◽  
Hydrodynamic Interactions ◽  
Squeeze Flow ◽  
Hydrodynamic Simulations ◽  
3D Simulations ◽  
Mason Number ◽  
Er Fluids

We report preliminary results for 3D simulations of a reduced model of electrorheological (ER) fluids. The hydrodynamic interactions are just squeeze flow lubrication and the electrostatic interactions that of point dipoles. In the low Mason number regime the same layer structure seen in earlier non-hydrodynamic simulations is found.

Structure Evolution of Electrorheological Fluids under Flow Conditions

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1806-1813 ◽  
Author(s):  
X. Tang ◽  
W. H. Li ◽  
X. J. Wang ◽  
P. Q. Zhang
Keyword(s):  
Layer Structure ◽  
Transparent Electrode ◽  
Electrorheological Fluids ◽  
Structure Evolution ◽  
Flow State ◽  
Flow Conditions ◽  
Transition Diagram ◽  
Conducting Film ◽  
Er Fluids ◽  
Induced Structure

Transparent electrode with a conducting film on a glass surface provides us a useful tool to observe the fired-induced structure formation in ER fluids directly under both quiescent and dynamic conditions. In this paper the flow and field-induced structure evolution in ER fluids will be studied in three flow conditions, i.e., (a) ER fluids flowing through a slit channel between two fixed parallel transparent electrodes, which construct a model ER valve, (b) ER fluids being sheared between two concentric transparent electrode tubes, which correspond to a conventional rotary rheometer and (c) ER fluids being sheared between two parallel plate disks, which correspond to an ER clutch. Shear-induced layer structure was observed even when the shear rate reaches 600 s -1. A tentative phase transition diagram between the layer structure and the homogeneous flow state will be given.

ELECTROSTATIC INTERACTIONS FOR PARTICLE ARRAYS IN ELECTRORHEOLOGICAL FLUIDS II: MEASUREMENTS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2895-2902 ◽  
Author(s):  
YING CHEN ◽  
H. CONRAD
Keyword(s):  
Shear Modulus ◽  
Electric Field ◽  
Shear Strain ◽  
Enhancement Factor ◽  
Shear Force ◽  
Electrostatic Interactions ◽  
Silicone Oil ◽  
Electrorheological Fluids ◽  
Proportionality Constant ◽  
Er Fluids

The force required to shear one-, two- and three-chain clusters of 230 µm dia. glass beads in silicone oil was measured. In each case the shear force was proportional to the shear strain, the proportionality constant increasing with electric field and number n of chains in the cluster. The derived shear modulus G also increased with n. An extrapolation of the present results suggests that a cluster of 4–5 chains would give the stress enhancement factor of 10–20 observed for real ER fluids.

Coating of Polyaniline with an Insulating Polymer to Improve the Power Efficiency of Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1931-1939 ◽  
Author(s):  
J. Akhavan ◽  
K. Slack ◽  
V. Wise ◽  
H. Block
Keyword(s):  
Power Efficiency ◽  
Electrorheological Fluids ◽  
Emeraldine Base ◽  
Heavy Duty ◽  
Base Form ◽  
Static Yield ◽  
High Fields ◽  
Er Fluids ◽  
Er Fluid ◽  
A Current

Currents drawn under high fields often present practical limitations to electrorheological (ER) fluids usefulness. For heavy-duty applications where large torques have to be transmitted, the power consumption of a ER fluid can be considerable, and for such uses a current density of ~100μ A cm -2 is often taken as a practical upper limit. This investigation was conducted into designing a fluid which has little extraneous conductance and therefore would demand less current. Selected semi-conducting polymers provide effective substrates for ER fluids. Such polymers are soft insoluble powdery materials with densities similar to dispersing agents used in ER formulations. Polyaniline is a semi-conducting polymer and can be used as an effective ER substrate in its emeraldine base form. In order to provide an effective ER fluid which requires less current polyaniline was coated with an insulating polymer. The conditions for coating was established for lauryl and methyl methacrylate. Results from static yield measurements indicate that ER fluids containing coated polyaniline required less current than uncoated polyaniline i.e. 0.5μ A cm -2. The generic type of coating was also found to be important.

scholarly journals Fabrication of Ultrathin MoS2 Nanosheets and Application on Adsorption of Organic Pollutants and Heavy Metals

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 504 ◽  
Author(s):  
Siyi Huang ◽  
Ziyun You ◽  
Yanting Jiang ◽  
Fuxiang Zhang ◽  
Kaiyang Liu ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Electrostatic Interactions ◽  
Large Scale ◽  
Layer Structure ◽  
Structural Characteristics ◽  
Hexagonal Phase ◽  
Two Dimensional ◽  
Mos2 Nanosheets ◽  
Hybrid Strategy ◽  
Ultrathin Mos2 Nanosheets

Owing to their peculiar structural characteristics and potential applications in various fields, the ultrathin MoS2 nanosheets, a typical two-dimensional material, have attracted numerous attentions. In this paper, a hybrid strategy with combination of quenching process and liquid-based exfoliation was employed to fabricate the ultrathin MoS2 nanosheets (MoS2 NS). The obtained MoS2 NS still maintained hexagonal phase (2H-MoS2) and exhibited evident thin layer-structure (1–2 layers) with inconspicuous wrinkle. Besides, the MoS2 NS dispersion showed excellent stability (over 60 days) and high concentration (0.65 ± 0.04 mg mL−1). The MoS2 NS dispersion also displayed evident optical properties, with two characteristic peaks at 615 and 670 nm, and could be quantitatively analyzed with the absorbance at 615 nm in the range of 0.01–0.5 mg mL−1. The adsorption experiments showed that the as-prepared MoS2 NS also exhibited remarkable adsorption performance on the dyes (344.8 and 123.5 mg g−1 of qm for methylene blue and methyl orange, respectively) and heavy metals (185.2, 169.5, and 70.4 mg g−1 of qm for Cd2+, Cu2+, and Ag+). During the adsorption, the main adsorption mechanisms involved the synergism of physical hole-filling effects and electrostatic interactions. This work provided an effective way for the large-scale fabrication of the two-dimensional nanosheets of transition metal dichalcogenides (TMDs) by liquid exfoliation.

scholarly journals Observable scattered light features from inclined and non-inclined planets embedded in protoplanetary discs

2019 ◽  
Vol 487 (4) ◽  
pp. 5372-5387
Author(s):  
Dylan L Kloster ◽  
M Flock
Keyword(s):  
Surface Density ◽  
Scattered Light ◽  
Intensity Variation ◽  
Theoretical Models ◽  
Upper Atmosphere ◽  
High Mass ◽  
Hydrodynamic Simulations ◽  
3D Simulations ◽  
2D And 3D ◽  
Protoplanetary Discs

ABSTRACT Over the last few years instruments such as VLT/SPHERE and Subaru/HiCIAO have been able to take detailed scattered light images of protoplanetary discs. Many of the features observed in these discs are generally suspected to be caused by an embedded planet, and understanding the cause of these features requires detailed theoretical models. In this work we investigate disc–planet interactions using the pluto code to run 2D and 3D hydrodynamic simulations of protoplanetary discs with embedded 30 and 300 M⊕ planets on both an inclined (i = 2.86°) and non-inclined orbit, using an α-viscosity of 4 × 10−3. We produce synthetic scattered light images of these discs at H-band wavelengths using the radiative transfer code radmc3d. We find that while the surface density evolution in 2D and 3D simulations of inclined and non-inclined planets remain fairly similar, their observational appearance is remarkably different. Most of the features seen in the synthetic H-band images are connected to density variations of the disc at around 3.3 scale heights above and below the mid-plane, which emphasizes the need for 3D simulations. Planets on sustained orbital inclinations disrupt the disc’s upper atmosphere and produce radically different observable features and intensity profiles, including shadowing effects and intensity variation of the order of 10–20 times the surrounding background. The vertical optical depth to the disc mid-plane for H-band wavelengths is τ ≈ 20 in the disc gap created by the high-mass planet. We conclude that direct imaging of planets embedded in the disc remains difficult to observe, even for massive planets in the gap.

ER fluids in the squeeze-flow mode: an application to vibration isolation

1992 ◽  
Vol 28 (1) ◽  
pp. 89-94 ◽  
Author(s):  
R. Stanway ◽  
J.L. Sproston ◽  
M.J. Prendergast ◽  
J.R. Case ◽  
C.E. Wilne
Keyword(s):  
Vibration Isolation ◽  
Squeeze Flow ◽  
Flow Mode ◽  
Er Fluids

Physicochemical Aspects of Forming Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1739-1749
Author(s):  
E.V. Korobko
Keyword(s):  
Physical Model ◽  
Experimental Results ◽  
Electrorheological Fluids ◽  
Er Fluids

Based on the experimental results and physical representations fo ER-fluids as a "poor" dielectric, a physical model of the ER-effect is elaborated and the main approaches to creation of electrosensitive fluids with desired properties are determined.

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.

Temperature Effect on Yield Stress of Electrorheological Fluids: Experimental Investigation

2006 ◽  
Vol 324-325 ◽  
pp. 173-176 ◽  
Author(s):  
Seung Bok Choi ◽  
Jung Woo Sohn ◽  
Y.S. Lee
Keyword(s):  
Temperature Effect ◽  
Yield Stress ◽  
Electrorheological Fluids ◽  
Shear Mode ◽  
Liquid Particle ◽  
Carrier Liquid ◽  
Field Dependent ◽  
Effect On Yield ◽  
Er Fluids ◽  
Rotational Shear

In the present paper, temperature effect on yield stress of electrorheological fluids is experimentally investigated. A rotational shear-mode type electroviscometer is designed and manufactured for the identification of Bingham characteristics of ER fluids. Optimization of ER fluids is undertaken with carrier liquid, particle and additive treatment and then four different ER fluids are prepared for the test. The field-dependent yield stress, current density and response time of optimized ER fluids are compared at various temperature conditions.

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