Measurement of single three-dimensional moduli to evaluate the effect of a uniform magnetic field on magnetorheological fluids

2020 ◽  
Vol 59 (3) ◽  
pp. 157-163
Author(s):  
Carlos Gracia-Fernández ◽  
Silvia Gómez-Barreiro ◽  
Ana Álvarez-García ◽  
Ana María Díaz-Díaz ◽  
Jorge López-Beceiro ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Three Dimensional ◽  
Magnetorheological Fluids

Visualizing Rheological Mechanism of Magnetorheological Fluids

2021 ◽  
Author(s):  
Yurui Shen ◽  
Dezheng Hua ◽  
Xinhua Liu ◽  
Weihua Li ◽  
Grzegorz Krolczyk ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Magnetic Dipole ◽  
Laser Scanning ◽  
Magnetic Particles ◽  
Three Dimensional ◽  
Confocal Laser Scanning Microscope ◽  
Magnetorheological Fluids ◽  
Confocal Laser ◽  
Observation Method

Abstract In order to study the rheological properties of aqueous magnetorheological fluids (MRFs) from microscopic point of view, an experimental observation method based on the fluorescence confocal laser scanning microscope is proposed to clearly produce the chain shape of the magnetic particles. Firstly, the mathematical model of the magnetic particles is established in a magnetic field using the magnetic dipole theory, and the MRFs with different fraction volumes and different magnetic fields are investigated. Furthermore, an aqueous MRFs experiment is prepared, in which the magnetic particles are combined with Alexa 488 fluorescent probe. On this basis, an observation method is innovatively developed using two-dimensional (2D) and three-dimensional (3D) image analysis by the fluorescence confocal microscope. The rheological mechanism of the aqueous MRFs is investigated using four different types of MRFs in an external magnetic field. The analysis results demonstrate that the simulation and experimental rheological properties of the MRFs are consistent with the magnetic dipole theory. Moreover, the proposed method is able to real-time observe the rheological process of the MRFs with a very high resolution, which ensures the correctness of the analysis results of the rheological mechanism.

Liquid-metal flow in a system of electrically coupled U-bends in a strong uniform magnetic field

1995 ◽  
Vol 299 ◽  
pp. 73-95 ◽  
Author(s):  
Sergei Molokov ◽  
Robert Stieglitz
Keyword(s):  
Magnetic Field ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Uniform Magnetic Field ◽  
Flow Direction ◽  
Metal Flow ◽  
Three Dimensional ◽  
Recirculatory Flow ◽  
The Magnetic Field ◽  
Very High

Liquid-metal magnetohydrodynamic flow in a system of electrically coupled U-bends in a strong uniform magnetic field is studied. The ducts composing the bends are electrically conducting and have rectangular cross-sections. It has been anticipated that very strong global electric currents are induced in the system, which modify the flow pattern and produce a very high pressure drop compared to the flow in a single U-bend. A detailed asymptotic analysis of flow for high values of the Harmann number (in fusion blanket applications of the order of 103−104) shows that circulation of global currents results in several types of peculiar flow patterns. In ducts parallel to the magnetic field a combination of helical and recirculatory flow types may be present and vary from one bend to another. The magnitude of the recirculatory motion may become very high depending on the flow-rate distribution between the bends in the system. The recirculatory flow may account for about 50% of the flow in all bends. In addition there are equal and opposite jets at the walls parallel to the magnetic field, which are common to any two bends. The pressure drop due to three-dimensional effects linearly increases with the number of bends in a system and may significantly affect the total pressure drop. To suppress this and some other unwelcome tendencies either the ducts perpendicular to the magnetic field should be electrically separated, or the flow direction in the neighbouring ducts should be made opposite, so that leakage currents cancel each other.

Squeeze behavior of magnetorheological fluids under constant volume and uniform magnetic field

2013 ◽  
Vol 22 (4) ◽  
pp. 045020 ◽  
Author(s):  
Chaoyang Guo ◽  
Xinglong Gong ◽  
Shouhu Xuan ◽  
Qifan Yan ◽  
Xiaohui Ruan
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Magnetorheological Fluids ◽  
Constant Volume

Inverse cascades in incompressible fluid and magnetofluid turbulence

1996 ◽  
Vol 56 (3) ◽  
pp. 467-491
Author(s):  
Murshed Hossain
Keyword(s):  
Magnetic Field ◽  
Incompressible Fluid ◽  
Uniform Magnetic Field ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Self Organization ◽  
Anisotropic Fluid ◽  
Uniform Rotation ◽  
Fluid Turbulence ◽  
Turbulent Fluctuations

Absolute equilibrium statistical theory and numerical simulations are reviewed in the context of inverse cascades in two- and three-dimensional incompressible fluid and magnetofluid turbulence. Turbulent fluctuations of physically interesting quantities undergo inverse cascade to larger spatial scales, leading to self-organization under certain circumstances. In particular, most systems with more than one quadratic ideal invariant, or, having some kind of imposed anisotropy, exhibit inverse cascades. Anisotropic fluid turbulence in the presence of a uniform rotation and magnetofluid turbulence in the presence of a uniform magnetic field are considered.

Weak magnetohydrodynamic turbulence and intermittency

2015 ◽  
Vol 770 ◽  
Author(s):  
R. Meyrand ◽  
K. H. Kiyani ◽  
S. Galtier
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Three Dimensional ◽  
Leading Order ◽  
Magnetohydrodynamic Turbulence ◽  
Asymptotic Regime ◽  
Resonant Interactions ◽  
Vector Separation ◽  
Parallel Current

Three-dimensional numerical simulation is used to investigate intermittency in incompressible weak magnetohydrodynamic turbulence with a strong uniform magnetic field $\boldsymbol{b}_{\mathbf{0}}$ and zero cross-helicity. At leading order, this asymptotic regime is achieved via three-wave resonant interactions with the scattering of a wave on a 2D mode for which $k_{\Vert }=0$. When the interactions with the 2D modes are artificially reduced, we show numerically that the system exhibits an energy spectrum with $k_{\bot }^{-3/2}$, whereas the expected exact solution with $k_{\bot }^{-2}$ is recovered with the full nonlinear system. In the latter case, strong intermittency is found when the vector separation of structure functions is taken transverse to $\boldsymbol{b}_{\mathbf{0}}$. This result may be explained by the influence of the 2D modes whose regime belongs to strong turbulence. In addition to shedding light on the origin of this intermittency, we derive a log-Poisson law, ${\it\zeta}_{p}=p/8+1-(1/4)^{p/2}$, which fits the data perfectly and highlights the important role of parallel current sheets.

scholarly journals Dynamo action in the presence of an imposed magnetic field

2009 ◽  
Vol 465 (2105) ◽  
pp. 1599-1616 ◽  
Author(s):  
D.W. Hughes ◽  
M.R.E. Proctor
Keyword(s):  
Magnetic Field ◽  
Linear Stability ◽  
Uniform Magnetic Field ◽  
Three Dimensional ◽  
Background Field ◽  
Magnetic Reynolds Number ◽  
Dynamo Action ◽  
Circularly Polarized ◽  
Forcing Function ◽  
Basic States

We consider the linear stability to three-dimensional perturbations of two-dimensional nonlinear magnetohydrodynamic basic states obtained from a specified forcing function in the presence of an imposed initially uniform magnetic field of strength B 0 . The forcing is chosen such that it drives the ‘circularly polarized’ (CP) flow of Galloway & Proctor ( Galloway & Proctor 1992 Nature 356 , 691–693) when B 0 =0. We first examine the properties of these basic states and their dependence on B 0 and the magnetic Reynolds number Rm . The linear stability of these states is then investigated. It is found that, at a given Rm , the presence of a background field is stabilizing. The results also allow us to speculate that, at a fixed value of B 0 , the growth of the unstable perturbations is ‘fast’, in the sense that the growth rate becomes independent of Rm as Rm →∞.

scholarly journals FERMI SURFACES OF CRYSTALS IN A HIGH MAGNETIC FIELD

2003 ◽  
Vol 02 (06) ◽  
pp. 603-610 ◽  
Author(s):  
J. BRÜNING ◽  
V. V. DEMIDOV ◽  
V. A. GEYLER
Keyword(s):  
Magnetic Field ◽  
Charged Particle ◽  
Dispersion Relation ◽  
Potential Theory ◽  
Explicit Form ◽  
High Magnetic Field ◽  
Uniform Magnetic Field ◽  
Three Dimensional ◽  
Fermi Surfaces ◽  
Zero Range

A method of building and investigation of the Fermi surfaces for three-dimensional crystals subjected to a uniform magnetic field is presented. The Hamiltonian of a charged particle in the crystal is treated in the framework of the zero-range potential theory. The dispersion relation for the Hamiltonian is obtained in an explicit form.

scholarly journals Synthesis and Characterization of Magnetorheological Fluids

2020 ◽  
Vol 9 (6) ◽  
pp. 272-277
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Temperature Stability ◽  
High Strength ◽  
Industrial Applications ◽  
Magnetorheological Fluids ◽  
Carrier Fluid ◽  
Performance Requirements ◽  
Mr Fluids ◽  
Mr Effect

Magnetorheological fluids (MRF) are mixture of ferromagnetic micron sized particles in silicon or hydraulic oil carrier fluid. By application of external varying strength magnetic field various physical properties of these fluids can be controlled and they becomes semi-solids depending on magnetic field strength application.MR fluids fulfill the desired performance requirements i.e. on application of magnetic field exhibits high shear and low initial viscosity, quick response , low hysteresis, low power consumption and temperature stability These special properties of MR fluids made them suitable for many type of industrial applications including machining. Hence fluids can be very effectively used in magnetorheological finishing process (MRF) which has unique feature of finishing truncated and complicated geometrical shapes and surfaces and capable of producing surface in nanometers. As surface finish is an important parameter in precision fits, product quality, and high-strength applications. The three dimensional surfaces finishing works such as different angled deep pockets or projections. Many industries have this type of i.e. mould & dies manufacturing, automobiles manufacturing, aerospace industry, semiconductor machining and optics machining etc. Such application leads to enhanced demand of nano-finishing of 3D surfaces without damaging surfaces/sub-surfaces. As due to change in properties because of change in composition the MR effect is also influenced. Therefore the composition of MR fluids is very important to achieve desired MR effect. The composition of magnetorheological fluids can be evaluated with the help of characterizations and desire MR fluid can be synthesized according to requirements of the process. This paper will explain in detail how we can synthesize and characterize the Magnetorheological fluids using state of the art equipments and can optimize their performance.

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