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Dynamics of a magnetic particle in a rotating magnetic field.

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Title: Dynamics of a magnetic particle in a rotating magnetic field.
Authors: Misra, Isha1 (AUTHOR), Kumaran, V.1 (AUTHOR) kumaran@iisc.ac.in
Source: Journal of Fluid Mechanics. 4/25/2026, Vol. 1033, p1-40. 40p.
Subjects: Magnetic particles, Particle dynamics analysis, Magnetic fields, Magnetic hysteresis, Viscous flow, Magnetic torque
Abstract: The orientation dynamics of a spheroidal magnetic particle in a viscous fluid subject to a rotating magnetic field is analysed for realistic two-parameter models for the magnetic moment. It is shown that the equations can be mapped onto those for a spherical magnetic particle in a steady magnetic field subject to shear flow. Time evolution equations for the azimuthal and meridional angles of the orientation vector are derived from the condition that the sum of the hydrodynamic and magnetic torques is zero in the viscous limit. One parameter is $\omega ^{\dagger}$ , the ratio of the magnetic field frequency and the particle viscous relaxation rate. For the non-hysteretic Langevin model, the second parameter is the ratio of the saturation moment $m_s$ and the susceptibility $\chi$ times the magnetic field $H,\!(m_s/\chi\! H)$. There is parallel corotation of the particle with the field for $\omega ^{\dagger} \lt \omega _b^{\dagger}$ , and parallel slip relative to the magnetic field for high $\omega ^{\dagger} \gt \omega _b^{\dagger}$ , where $\omega _b^{\dagger}$ is the breakdown frequency. For the hysteretic Stoner–Wohlfarth model, the second parameter is $h$ , the ratio of the Zeeman energy and the anisotropy energy due to the misalignment between the moment and the particle axis. There are three states, parallel corotation for low $\omega ^{\dagger}$ , precessed corotation for high $\omega ^{\dagger}$ and low $h$ , where the orientation precesses relative to the axis of rotation of the magnetic field, and parallel slip at high $\omega ^{\dagger}$ and high $h$. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
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Header DbId: egs
DbLabel: Engineering Source
An: 193952095
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
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  Data: Dynamics of a magnetic particle in a rotating magnetic field.
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  Data: <searchLink fieldCode="AR" term="%22Misra%2C+Isha%22">Misra, Isha</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kumaran%2C+V%2E%22">Kumaran, V.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> kumaran@iisc.ac.in</i>
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Fluid+Mechanics%22">Journal of Fluid Mechanics</searchLink>. 4/25/2026, Vol. 1033, p1-40. 40p.
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  Data: <searchLink fieldCode="DE" term="%22Magnetic+particles%22">Magnetic particles</searchLink><br /><searchLink fieldCode="DE" term="%22Particle+dynamics+analysis%22">Particle dynamics analysis</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+fields%22">Magnetic fields</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+hysteresis%22">Magnetic hysteresis</searchLink><br /><searchLink fieldCode="DE" term="%22Viscous+flow%22">Viscous flow</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+torque%22">Magnetic torque</searchLink>
– Name: Abstract
  Label: Abstract
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  Data: The orientation dynamics of a spheroidal magnetic particle in a viscous fluid subject to a rotating magnetic field is analysed for realistic two-parameter models for the magnetic moment. It is shown that the equations can be mapped onto those for a spherical magnetic particle in a steady magnetic field subject to shear flow. Time evolution equations for the azimuthal and meridional angles of the orientation vector are derived from the condition that the sum of the hydrodynamic and magnetic torques is zero in the viscous limit. One parameter is $\omega ^{\dagger}$ , the ratio of the magnetic field frequency and the particle viscous relaxation rate. For the non-hysteretic Langevin model, the second parameter is the ratio of the saturation moment $m_s$ and the susceptibility $\chi$ times the magnetic field $H,\!(m_s/\chi\! H)$. There is parallel corotation of the particle with the field for $\omega ^{\dagger} \lt \omega _b^{\dagger}$ , and parallel slip relative to the magnetic field for high $\omega ^{\dagger} \gt \omega _b^{\dagger}$ , where $\omega _b^{\dagger}$ is the breakdown frequency. For the hysteretic Stoner–Wohlfarth model, the second parameter is $h$ , the ratio of the Zeeman energy and the anisotropy energy due to the misalignment between the moment and the particle axis. There are three states, parallel corotation for low $\omega ^{\dagger}$ , precessed corotation for high $\omega ^{\dagger}$ and low $h$ , where the orientation precesses relative to the axis of rotation of the magnetic field, and parallel slip at high $\omega ^{\dagger}$ and high $h$. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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    Identifiers:
      – Type: doi
        Value: 10.1017/jfm.2026.11360
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      – Code: eng
        Text: English
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      Pagination:
        PageCount: 40
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    Subjects:
      – SubjectFull: Magnetic particles
        Type: general
      – SubjectFull: Particle dynamics analysis
        Type: general
      – SubjectFull: Magnetic fields
        Type: general
      – SubjectFull: Magnetic hysteresis
        Type: general
      – SubjectFull: Viscous flow
        Type: general
      – SubjectFull: Magnetic torque
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      – TitleFull: Dynamics of a magnetic particle in a rotating magnetic field.
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            NameFull: Misra, Isha
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            NameFull: Kumaran, V.
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            – D: 25
              M: 04
              Text: 4/25/2026
              Type: published
              Y: 2026
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