Study of the magnetic force delivered by an actuator with nonlinear ferrofluid and permanent magnets

Olaru, Radu; Arcire, Alexandru; Petrescu, Camelia; Mihai, Marius-Mugurel

doi:10.1002/tee.22331

Cited by 13 publications

(6 citation statements)

References 17 publications

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“…The displacement vector from the current element i m dzdl over the outer side surface of the ring magnet to the point P(C, , D) can be expressed as (12) where e x , e y , and e z are the unit vector of X-axis, Y-axis, and Z-axis in cartesian coordinate system, respectively.…”

Section: Calculation Of the Magnetic Field Strength In Magnetic Fluidmentioning

confidence: 99%

“…Later in the book titled "ferrohydrodynamic", Rosensweig gave a detailed description on the particular magnetic levitation force (selfsuspension buoyancy) by means of magnetic fluid stress tensor [3]. Up to now, this property of magnetic fluid has been exploited in many innovative devices, such as dampers [4][5][6], sensors [7][8][9][10][11], actuators [12][13][14], bearings [15,16], micromechanical system [17][18][19] and so on.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Research on the Axial Magnetic Levitation Force Acting on the Ring Magnet Suspended in Magnetic Fluid : Considering a Radial Eccentricity

Yu¹,

Li²,

Di³

et al. 2019

JMAG

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The self-suspension of magnet in magnetic fluid has been widely used in micromechanical systems, sensors, and dampers. The magnetic field associated with the ring magnet is obtained by numerical calculation and simulation through which the axial magnetic levitation force is calculated, and the numerical calculation, simulation, and experimental results agree with each other. The influence of the radial eccentricity of the ring magnet on the axial magnetic levitation force is studied, the ring magnet will experience a maximum axial magnetic levitation force without radial eccentricity. With the increase of radial eccentricity and the decrease of the distance between the bottom of the ring magnet and container, the axial magnetic levitation force will continue to decrease. But it is worth noting that the magnitude of the change caused by radial eccentricity is negligible compared to that of the axial magnetic levitation force.

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Section: Calculation Of the Magnetic Field Strength In Magnetic Fluidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Research on the Axial Magnetic Levitation Force Acting on the Ring Magnet Suspended in Magnetic Fluid : Considering a Radial Eccentricity

Yu¹,

Li²,

Di³

et al. 2019

JMAG

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show abstract

“…As the magnetic fields can be generated using electromagnets integrable to electronics, the process has a tremendous potential for smart sensor applications. Such efforts have already been made, for example the development of magnetic actuators (Olaru et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Levitation of non-magnetizable droplet inside ferrofluid

Singh

Das

2018

J. Fluid Mech.

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The central theme of this work is that a stable levitation of a denser non-magnetizable liquid droplet, against gravity, inside a relatively lighter ferrofluid -a system barely considered in ferrohydrodynamics -is possible, and exhibits unique interfacial features; the stability of the levitation trajectory, however, is subject to an appropriate magnetic field modulation. We explore the shapes and the temporal dynamics of a plane non-magnetizable droplet levitating inside ferrofluid against gravity due to a spatially complex, but systematically generated, magnetic field in two dimensions. The coupled set of Maxwell's magnetostatic equations and the flow dynamic equations is integrated computationally, utilizing a conservative finite-volume based second order pressure projection algorithm combined with the front-tracking algorithm for the advection of the interface of the droplet. The dynamics of the droplet is studied under both the constant ferrofluid magnetic permeability assumption as well as for more realistic field dependent permeability described by the Langevin's non-linear magnetization model. Due to the non-homogeneous nature of the magnetic field, unique shapes of the droplet during its levitation, and at its steady state, are realized. The complete spatio-temporal response of the droplet is a function of the Laplace number La, the magnetic Laplace number La m , and the Galilei number Ga; through detailed simulations we separate out individual roles played by these non-dimensional parameters. The effect of the viscosity ratio, the stability of the levitation path and the possibility of existence of multiple-stable equilibrium states is investigated. We find, for certain conditions on the viscosity ratio, that there can be developments of cusps and singularities at the droplet surface; this phenomenon we also observe experimentally and compare with the simulations. Our simulations closely replicate the singular projection on the surface of the levitating droplet. Finally, we present an dynamical model for the vertical trajectory of the droplet. This model reveals a condition for the onset of levitation and the relation for the equilibrium levitation height. The linearization of the model around the steady state captures that the nature of the equilibrium point goes under a transition from being a spiral to a node depending upon the control parameters, which essentially means that the temporal route to the equilibrium can be either monotonic or undulating. The analytical model for the droplet trajectory is in close agreement with the detailed simulations.

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“…The magnetic nanoparticles coated with surfactant are uniformly dispersed in the liquid carrier. As a new type of functional material with fluidity and magnetism, the combi nation of fluidity and magnetism of magnetic fluid has been exploited in many applications, such as sealing [1], sensors and actuators [2][3][4][5][6], shock absorber [7], positioning system [8,9] and so on. One of the most important properties of magn etic fluid is that a magnet, whose density is greater than that of magnetic fluid, can be stably suspended in the magn etic fluid.…”

Section: Introductionmentioning

confidence: 99%

A novel method for calculating and measuring the second-order buoyancy experienced by a magnet immersed in magnetic fluid

Yu¹,

Du²,

Li³

2017

J. Phys. D: Appl. Phys.

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The phenomenon whereby an object whose density is greater than magnetic fluid can be suspended stably in magnetic fluid under the magnetic field is one of the peculiar properties of magnetic fluids. Examples of applications based on the peculiar properties of magnetic fluid are sensors and actuators, dampers, positioning systems and so on. Therefore, the calculation and measurement of magnetic levitation force of magnetic fluid is of vital importance. This paper concerns the peculiar second-order buoyancy experienced by a magnet immersed in magnetic fluid. The expression for calculating the second-order buoyancy was derived, and a novel method for calculating and measuring the second-order buoyancy was proposed based on the expression. The second-order buoyancy was calculated by ANSYS and measured experimentally using the novel method. To verify the novel method, the second-order buoyancy was measured experimentally with a nonmagnetic rod stuck on the top surface of the magnet. The results of calculations and experiments show that the novel method for calculating the second-order buoyancy is correct with high accuracy. In addition, the main causes of error were studied in this paper, including magnetic shielding of magnetic fluid and the movement of magnetic fluid in a nonuniform magnetic field.

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Study of the magnetic force delivered by an actuator with nonlinear ferrofluid and permanent magnets

Cited by 13 publications

References 17 publications

Research on the Axial Magnetic Levitation Force Acting on the Ring Magnet Suspended in Magnetic Fluid : Considering a Radial Eccentricity

Research on the Axial Magnetic Levitation Force Acting on the Ring Magnet Suspended in Magnetic Fluid : Considering a Radial Eccentricity

Levitation of non-magnetizable droplet inside ferrofluid

A novel method for calculating and measuring the second-order buoyancy experienced by a magnet immersed in magnetic fluid

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