Effect of aggregates on the magnetization property of ferrofluids: A model of gaslike compression

Li, Jian; Huang, Yan; Liu, Xiaodong; Lin, Y.S.; Liu, Bai; Li, Qiang

doi:10.1016/j.stam.2007.04.007

Cited by 43 publications

(33 citation statements)

References 40 publications

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“…In this case the aggregates formation can be modeled by an l-g type of a phase transition in the framework of the simple mean field theory [22] or the isotropic potential model [26,36]. In the case of a stabilized FF, an ascending binodal curve theoretical dependence [10,24,25] matches very few experimental reports (the reference in the [24]). …”

Section: B Phase Diagrammentioning

confidence: 84%

“…Some of these theories are phenomenological (e.g. [25]). Examples of the simplification related assumptions of these models are following: the nearest-neighbors approximation of configurational integral [10], the isotropic potential approximation [36], a dipole-dipole interaction as a perturbation [24], a very diluted phase consideration [37,38], a zero or infinite value of an external magnetic field [10], others [39].…”

Section: Introductionmentioning

confidence: 99%

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Ferrofluid nucleus phase transitions in an external uniform magnetic field

Tanygin¹,

Shulyma²,

Kovalenko³

et al. 2015

Chinese Phys. B

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The phase transition between a massive dense phase and a diluted superparamagnetic phase has been studied by means of a direct molecular dynamics simulation. The equilibrium structures of the ferrofluid aggregate nucleus are obtained for different values of a temperature and an external magnetic field magnitude. An approximate match of experiment and simulation has been shown for the ferrofluid phase diagram coordinates "field-temperature". The provided phase coexistence curve has an opposite trend comparing to some of known theoretical results. This contradiction has been discussed. For given experimental parameters, it has been concluded that the present results describe more precisely the transition from linear chains to a dense globes phase. The theoretical concepts which provide the opposite binodal curve dependency trend match other experimental conditions: a diluted ferrofluid, a high particle coating rate, a high temperature, and/or a less particles coupling constant value.

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Section: B Phase Diagrammentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Ferrofluid nucleus phase transitions in an external uniform magnetic field

Tanygin¹,

Shulyma²,

Kovalenko³

et al. 2015

Chinese Phys. B

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“…E-mail: aizhong@swu.edu.cn and ferrofluids, M, can be described by the Langevin equation for a paramagnetic system 6,7 as The interaction between particles plays an important role in the deviation. 10,11 Also, there was a loss in magnetization of the ferrofluids, i.e. the apparent M f.s could be less than ϕ v M p.s , or M f.s /ϕ v < M p.s , 6,12 where M f.s /ϕ v is termed the reduced magnetization of the ferrofluids and presents the effective magnetization of the solid phase.…”

Section: Introductionmentioning

confidence: 99%

Investigation into loss in ferrofluid magnetization

Gong

Lin

et al. 2014

AIP Advances

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Ferrofluids containing γ-Fe2O3/Ni2O3 nanoparticles (not chemically treated) were synthesized using water and mixed water–glycerol as carrier liquid and the ferrofluid viscosity was modified by varying the glycerol content in the carrier liquid. The apparent magnetization of the ferrofluids decreased with increasing glycerol content. The loss in magnetization is described by the ratio of effective magnetic volume fraction to physical volume fraction of nanoparticles in the ferrofluids as a characteristic parameter. We ascribe the loss to the formation of “dead aggregates” having a ring-like structure of closed magnetic flux rather than to any chemical reaction. Such dead aggregates exist in zero magnetic field and do not contribute to the magnetization in the low or high field regime, so that the effective magnetic volume fraction in the ferrofluids decrease. An increase in carrier liquid viscosity is similar to a weakening of the thermal effect, so the number of dead aggregates increases and the magnetization decreases in inverse proportion to the viscosity. This relationship between the apparent magnetization and ferrofluid carrier liquid viscosity can be termed the “viscomagnetic effect”.

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“…is the bulk-mean volume fraction of the nanoparticles, φ int is the volume fraction of the nanoparticles in aggregation due to local magnetic field and is given by [60,76],…”

Section: Heat Flux Vectormentioning

confidence: 99%

Effects of Anisotropic Thermal Conductivity and Lorentz Force on the Flow and Heat Transfer of a Ferro-Nanofluid in a Magnetic Field

Yan

Massoudi

et al. 2017

Energies

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Abstract:In this paper, we study the effects of the Lorentz force and the induced anisotropic thermal conductivity due to a magnetic field on the flow and the heat transfer of a ferro-nanofluid. The ferro-nanofluid is modeled as a single-phase fluid, where the viscosity depends on the concentration of nanoparticles; the thermal conductivity shows anisotropy due to the presence of the nanoparticles and the external magnetic field. The anisotropic thermal conductivity tensor, which depends on the angle of the applied magnetic field, is suggested considering the principle of material frame indifference according to Continuum Mechanics. We study two benchmark problems: the heat conduction between two concentric cylinders as well as the unsteady flow and heat transfer in a rectangular channel with three heated inner cylinders. The governing equations are made dimensionless, and the flow and the heat transfer characteristics of the ferro-nanofluid with different angles of the magnetic field, Hartmann number, Reynolds number and nanoparticles concentration are investigated systematically. The results indicate that the temperature field is strongly influenced by the anisotropic behavior of the nanofluids. In addition, the magnetic field may enhance or deteriorate the heat transfer performance (i.e., the time-spatially averaged Nusselt number) in the rectangular channel depending on the situations.

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Effect of aggregates on the magnetization property of ferrofluids: A model of gaslike compression

Cited by 43 publications

References 40 publications

Ferrofluid nucleus phase transitions in an external uniform magnetic field

Ferrofluid nucleus phase transitions in an external uniform magnetic field

Investigation into loss in ferrofluid magnetization

Effects of Anisotropic Thermal Conductivity and Lorentz Force on the Flow and Heat Transfer of a Ferro-Nanofluid in a Magnetic Field

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