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Paper   IPM / P / 14629
School of Physics
  Title:   Dynamics of magnetic nano-flake vortices in Newtonian fluids
1.  N. Bazazzadeh
2.  S.M. Mohseni
3.  A. Khavasi
4.  M.I. Zibaii
5.  S.M.S. Movahed
6.  G.R. Jafari
  Status:   Published
  Journal: Journal of Magnetism and Magnetic Materials
  Vol.:  419
  Year:  2016
  Pages:   547-552
  Supported by:  IPM
We study the rotational motion of nano-flake ferromagnetic discs suspended in a Newtonian fluid, as a potential material owing the vortex-like magnetic configuration. Using analytical expressions for hydrodynamic, magnetic and Brownian torques, the stochastic angular momentum equation is determined in the dilute limit conditions under applied magnetic field. Results are compared against experimental ones and excellent agreement is observed. We also estimate the uncertainty in the orientation of the discs due to the Brownian torque when an external magnetic field aligns them. Interestingly, this uncertainty is roughly proportional to the ratio of thermal energy of fluid to the magnetic energy stored in the discs. Our approach can be implemented in many practical applications including biotechnology and multi-functional fluidics.

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