scholarly journals Numerical study of the influence of diffusion of magnetic particles on equilibrium shapes of a free magnetic fluid surface

2009 ◽  
Vol 14 (4) ◽  
pp. 1403-1409 ◽  
Author(s):  
Sergey Beresnev ◽  
Viktor Polevikov ◽  
Lutz Tobiska
Keyword(s):  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Fluid Surface ◽  
Equilibrium Shapes

scholarly journals NUMERICAL STUDY OF THE ROSENSWEIG INSTABILITY IN A MAGNETIC FLUID SUBJECT TO DIFFUSION OF MAGNETIC PARTICLES

2010 ◽  
Vol 15 (2) ◽  
pp. 223-233 ◽  
Author(s):  
Olga Lavrova ◽  
Viktor Polevikov ◽  
Lutz Tobiska
Keyword(s):  
Magnetic Field ◽  
Free Surface ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Fluid Layer ◽  
Classical Problem ◽  
Parametric Representation ◽  
Field Configuration ◽  
Wide Range

The present study is devoted to the classical problem on stability of a magnetic fluid layer under the influence of gravity and a uniform magnetic field. A periodical peak‐shaped stable structure is formed on the fluid surface when the applied magnetic field exceeds a critical value. The mathematical model describes a single peak in the pattern assuming axial symmetry of the peak shape. The field configuration in the whole space, the magnetic particle concentration inside the fluid and the free surface structure are unknown quantities in this model. The unknown free surface is treated explicitly, using a parametric representation with respect to the arc length. The nonlinear problem is discretized by means of a finite element method for the Maxwell's equations and a finite‐difference method for the free surface equations. Numerical modelling allows to get over‐critical equilibrium free surface shapes in a wide range of applied field intensities. Our numerical results show a significant influence of the particle diffusion on the overcritical shapes.

A magnetic super lattice

1987 ◽  
Vol 45 ◽  
pp. 360-361 ◽  
Author(s):  
M.D. Bentzon ◽  
J. v. Wonterghem ◽  
A. Thölén
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Carbon Film ◽  
Thick Layer ◽  
Amorphous Iron ◽  
Super Lattice ◽  
Carrier Liquid ◽  
Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

The Analysis on the Starting Friction Torque Increase of Magnetic Fluid Revolving Sealing

2013 ◽  
Vol 275-277 ◽  
pp. 429-432 ◽  
Author(s):  
Yu Qiang Cai ◽  
Na Xing
Keyword(s):  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Influence Factor ◽  
Magnetic Field Gradient ◽  
Friction Torque ◽  
Key Factor ◽  
Lower Temperature ◽  
Change Of Microstructure ◽  
Starting Torque ◽  
Main Influence

Abstract. Magnetic fluid revolving sealing is widely used in modern industry. In the process of application, it is founded that the starting friction torque is very large, particularly at lower temperature. This problem has become a key factor restricting the application of magnetic fluid rotation sealing. In this paper, the mechanism of starting torque increase is analyzed, based on the change of microstructure and its viscosity. After analysis , such conclusion is obtained , which can be described: to a certain sealing structure, the type of magnetic fluid, size distribution of magnetic particles as well as the working condition concluding temperature, magnetic field gradient and the revolving velocity of shaft is the main influence factor of starting friction torque . It is very useful to reduce the starting friction torque.

scholarly journals Instability of a magnetic fluid drop in a capillary: a numerical study

2008 ◽  
Vol 44 (2) ◽  
pp. 183-190 ◽  
Author(s):  
O. Lavrova ◽  
V. Polevikov ◽  
L. Tobiska
Keyword(s):  
Magnetic Fluid ◽  
Numerical Study ◽  
Fluid Drop

scholarly journals The shape of the magnetic fluid surface above a magnetizable sphere in a uniform magnetic field

2015 ◽  
Vol 60 (10) ◽  
pp. 1437-1442
Author(s):  
V. G. Bashtovoi ◽  
A. A. Motsar ◽  
V. A. Naletova ◽  
A. G. Reks
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Uniform Magnetic Field ◽  
Fluid Surface

Investigation of Enhancement in Pool Boiling Heat Transfer of a Binary Temperature Sensitive Magnetic Fluid

2013 ◽  
Author(s):  
Giti Karimi-Moghaddam ◽  
Richard D. Gould ◽  
Subhashish Bhattacharya
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Magnetic Fluid ◽  
Boiling Heat Transfer ◽  
Magnetic Particles ◽  
Pool Boiling ◽  
Simulation Software ◽  
Temperature Sensitive ◽  
Magnetic Field Effects ◽  
Pool Boiling Heat Transfer

In this paper, the performance of pool boiling heat transfer using a binary temperature sensitive magnetic fluid in the presence of a non-uniform magnetic field is investigated numerically. By using a binary magnetic fluid, enhanced boiling heat transfer is obtained by thermomagnetic convection without deterioration of properties of the fluid. This work is aimed at gaining a qualitative understanding the magnetic field effects on boiling heat transfer enhancement of magnetic fluids. In order to accomplish this, the boiling process and the effects of position of the external magnetic field on flow pattern and heat transfer are investigated in a 2D rectangular domain using COMSOL Multiphysics simulation software. Finally, the boiling curves for a binary temperature sensitive magnetic fluid and its base fluid (without magnetic particles) are compared for various applied heat flux magnitudes.

A numerical study on the effect of static magnetic field on the hemodynamics of magnetic fluid in biological porous media

2020 ◽  
Vol 141 (5) ◽  
pp. 1543-1558
Author(s):  
Seyed Mahdi Hosseinikhah ◽  
Borhan Beigzadeh ◽  
Majid Siavashi ◽  
Mahdi Halabian
Keyword(s):  
Magnetic Field ◽  
Porous Media ◽  
Static Magnetic Field ◽  
Magnetic Fluid ◽  
Numerical Study

Heat Transfer Enhancement in Pipe Flow Problems of a Magnetic Fluid

2007 ◽  
Author(s):  
P. N. Kaloni ◽  
F. Lin ◽  
G. W. Rankin
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Internal Rotation ◽  
Magnetic Fluid ◽  
Pipe Flow ◽  
Magnetic Particles ◽  
Transfer Enhancement ◽  
Cylindrical Pipe ◽  
Flow Problems ◽  
Dissipation Term

Analytical solutions are presented for the temperature distribution and heat transfer coefficient in the forced convection of a magnetic fluid in cylindrical pipe flow. The theory of a ferro-fluid with internal rotation of magnetic particles is employed. Effects of the conventional dissipation term along with the dissipation reflecting the effect of internal rotation are considered and discussed. By computing the Nusselt number in various cases, the influence that different parameters have on the flow are revealed.

scholarly journals Numerical study of magnetic particles mixing in waste water under an external magnetic field

2020 ◽  
Vol 69 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Christos Liosis ◽  
Evangelos G. Karvelas ◽  
Theodoros Karakasidis ◽  
Ioannis E. Sarris
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Low Frequency ◽  
Water And Wastewater Treatment ◽  
Novel Approach ◽  
Optimal Value ◽  
Frequency Optimum ◽  
Combined Action ◽  
Aligned Magnetic Field

Abstract The combination of nanotechnology and microfluidics may offer an effective water and wastewater treatment. A novel approach combines the use of magnetic particles which can capture heavy metal impurities in microfluidic ducts. The purpose of this study is to investigate the mixing mechanism of two water streams, one with magnetic particles and the other with wastewater. The optimum mixing is obtained when particles are uniformly distributed along the volume of water in the duct for the combined action of a permanent, spatially and temporally aligned magnetic field. Results showed that mixing is enhanced as the frequency of the magnetic field decreases or its amplitude increases, while magnetic gradient is found to play an insignificant role in the present configuration. Moreover, for simulations with low frequency, the mean concentration of particles is found to be twice as high as compared to the cases with higher frequency. Optimum distribution of particles inside the micromixer is observed for the combination of 0.6 T, 8 T/m and 5 Hz for the magnetic magnitude, gradient and frequency, respectively, where concentration reaches the optimal value of 0.77 mg/mL along the volume of the duct.

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