scholarly journals Magnetic fluid bridge between two cones and a cylinder in the magnetic field of a current-carrying wire

2018 ◽  
Vol 185 ◽  
pp. 09010
Author(s):  
Alexandra S. Vinogradova ◽  
Vladimir A. Turkov ◽  
Vera A. Naletova
Keyword(s):  
Magnetic Field ◽  
Pressure Drop ◽  
Numerical Modelling ◽  
Magnetic Fluid ◽  
Surface Shape ◽  
Zero Current ◽  
The Wire ◽  
The Magnetic Field ◽  
A Current ◽  
Hysteresis Phenomena

A magnetic fluid (MF) changes its surface shape in the magnetic field of a current-carrying wire while the current is changing. In the present paper, we propose to study a MF bridge which can open or close the channel formed by two cones and a cylinder by imposing the magnetic field of a wire. Numerical modelling of the bridge behavior for different values of MF volumes and currents in the wire is done for two cases: when the MF wets and does not wet surrounding solid boundaries. It is shown that the presence of limiting cones allows the MF to sustain the pressure drop which is much higher in case of non-wetting than in case of wetting. In case of wetting, the MF cannot sustain any pressure drop at low currents, but in case of non-wetting, the MF can do it even at zero current. It is found that in case of non-wetting, spasmodic and hysteresis phenomena are possible for some values of MF volumes and currents in the wire. The use of a MF in valves, dispensers and pumps is one of possible actuation methods.

scholarly journals Meniscus of a Magnetic Fluid in the Field of a Current-Carrying Wire: Three-Dimensional Numerical Simulations

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 775
Author(s):  
Paul-Benjamin Eißman ◽  
Stefan Odenbach ◽  
Adrian Lange
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Material Properties ◽  
Three Dimensional ◽  
Applied Current ◽  
Great Strength ◽  
Magnetisation Curve ◽  
The Wire ◽  
The Magnetic Field ◽  
A Current

Three-dimensional calculations of the meniscus of a magnetic fluid placed around a current carrying vertical and cylindrical wire are presented. Based on the material properties of experimentally used magnetic fluids, the numerically determined menisci are compared with the experimentally measured ones reported by May. The comparison is made for a linear law of magnetisation as well as for the experimentally measured nonlinear magnetisation curve. Up to moderate strengths of the applied current ( I < = 45 A), i.e., up to moderate strengths of the magnetic field close to the wire, the calculated profiles agree satisfyingly with the experimentally measured ones for a linear as well as for a nonlinear law of magnetisation. At a great strength of the applied current ( I = 70 A), i.e., at a large strength of the magnetic field close to the wire, the agreement is less good than in the range up to moderate strengths. Our analysis revealed that the numerically assumed isothermal conditions are not present in the experiment, particularly at the great strength of the applied current. A control of the temperature in the experiment and the implementation of a coupled thermal model in the numerics are considered the most relevant future steps for an improved agreement.

scholarly journals The galvanometer constant of a circular coil of many windings

1935 ◽  
Vol 150 (871) ◽  
pp. 487-494
Keyword(s):  
Magnetic Field ◽  
Rectangular Channel ◽  
Number Of Layers ◽  
Circular Coil ◽  
Absolute Measure ◽  
The Mean ◽  
The Wire ◽  
The Magnetic Field ◽  
A Current

In a number of investigations the strength of the magnetic field at the centre of a circular coil of many turns due to a current in the coil is required. Among these may be mentioned the determination of the ampere in absolute measure by the method adopted by Rayleigh and Sidgwick. Let a be the mean radius of the coil, N the number of turns, 2 b and 2 c the axial and radial dimensions of the rectangular channel in which the coil is wound, d and d 0 the covered, α bare diameters of the wire, m the number of windings in a layer, and n the number of layers.

Study of MFM Application in Semiconductor Failure Analysis

2004 ◽  
Author(s):  
Way-Jam Chen ◽  
Lily Shiau ◽  
Ming-Ching Huang ◽  
Chia-Hsing Chao
Keyword(s):  
Magnetic Field ◽  
Failure Analysis ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Current Flow ◽  
Force Microscopy ◽  
The Magnetic Field ◽  
A Current

Abstract In this study we have investigated the magnetic field associated with a current flowing in a circuit using Magnetic Force Microscopy (MFM). The technique is able to identify the magnetic field associated with a current flow and has potential for failure analysis.

Swirling Flow of Magnetic Fluid in Multi-Pole Rotating Magnetic Field

2003 ◽  
Author(s):  
Kenichi Kamioka ◽  
Ryuichiro Yamane
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Circular Cylinder ◽  
Phase Velocity ◽  
Magnetic Fluid ◽  
Swirling Flow ◽  
Peak Velocity ◽  
Rotating Magnetic Field ◽  
Outer Periphery ◽  
The Magnetic Field

The experiments are conducted on the magnetic fluid flow induced by the multi-pole rotating magnetic field in a circular cylinder. The numbers of poles are two, four, six, eight and twelve. The applied electric current and frequency are 2∼6 A and 20∼60 Hz, respectively. The peak velocity of the flow increases with the increase in the strength and the phase velocity of the magnetic field. As the increase in the number of poles, the flow shifts to the outer periphery.

Particle Transport in a Turbulent Square Duct Flow With an Imposed Magnetic Field

2013 ◽  
Author(s):  
Rui Liu ◽  
Surya P. Vanka ◽  
Brian G. Thomas
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Continuous Flow ◽  
Duct Flow ◽  
Deposition Rates ◽  
Square Duct ◽  
Side Walls ◽  
Volume Method ◽  
The Magnetic Field ◽  
A Current

In this paper we study the particle transport and deposition in a turbulent square duct flow with an imposed magnetic field using Direct Numerical Simulations (DNS) of the continuous flow. A magnetic field induces a current and the interaction of this current with the magnetic field generates a Lorentz force which brakes the flow and modifies the flow structure. A second-order accurate finite volume method in time and space is used and implemented on a GPU. Particles are injected at the entrance to the duct continuously and their rates of deposition on the duct walls are computed for different magnetic field strengths. Because of the changes to the flow due to the magnetic field, the deposition rates are different on the top and bottom walls compared to the side walls. This is different than in a non-MHD square duct flow, where quadrant (and octant) symmetry is obtained.

scholarly journals The study of the specific resistance of bismuth crystals and its change in strong magnetic fields and some allied problems

1928 ◽  
Vol 119 (782) ◽  
pp. 358-443 ◽  
Keyword(s):  
Magnetic Field ◽  
Specific Resistance ◽  
Cleavage Plane ◽  
Time Lag ◽  
General View ◽  
Time Lags ◽  
Strong Magnetic Fields ◽  
First Moment ◽  
The Magnetic Field ◽  
A Current

It is well known that in a magnetic field bismuth shows a greater change of resistance than any other substance, and it is also known that in the case of a crystal this phenomenon varies very much with the orientation of the crystal. A great deal of literature exists on this subject. The general view of the phenomenon is that the increase of resistance is largest when the cleavage plane of the crystal is parallel to the magnetic field, and when the current is flowing perpendicular to it. It is also known that the resistance in a magnetic field increases very rapidly with decreasing temperature. A complication in all these phenomena arises through certain time lags. When a current is passed through bismuth placed in a magnetic field, the resistance at the first moment is large, and then gradually decreases to its final value. This time lag accounts for the fact, first discovered by Lenard, that bismuth has a larger resistance for alternating currents than for direct currents. This phenomenon also depends on the crystal state of the bismuth.

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