4 research outputs found
Ferrohydrodynamics: testing a new magnetization equation
A new magnetization equation recently derived from irreversible
thermodynamics is employed to the calculation of an increase of ferrofluid
viscosity in a magnetic field. Results of the calculations are compared with
those obtained on the basis of two well-known magnetization equations. One of
the two was obtained phenomenologically, another one was derived
microscopically from the Fokker-Planck equation. It is shown that the new
magnetization equation yields a quite satisfactory description of
magnetiviscosity in the entire region of magnetic field strength and the flow
vorticity. This equation turns out to be valid -- like the microscopically
derived equation but unlike the former phenomenological equation -- even far
from equilibrium, and so it should be recommended for further applications.Comment: 4 pages, 3 figures, Submitted to Phys. Rev.
Comment on "Magnetoviscosity and relaxation in ferrofluids"
It is shown and discussed how the conventional system of hydrodynamic
equations for ferrofluids was derived. The set consists of the equation of
fluid motion, the Maxwell equations, and the magnetization equation. The latter
was recently revised by Felderhof [Phys. Rev. E, v.62, p.3848 (2000)]. His
phenomenological magnetization equation looks rather like corresponding
Shliomis' equation, but leads to wrong consequences for the dependence of
ferrofluid viscosity and magnetization relaxation time on magnetic field.Comment: 6 pages, 1 figure, Submitted to Phys. Rev.
Comment on "Novel Convective Instabilities in a Magnetic Fluid"
Comment on the paper "Novel Convective Instabilities in a Magnetic Fluid" by
W. Luo, T. Du, and J. Huang, Phys. Rev. Lett., v.82, p.4134 (1999).Comment: 1 page, 1 figure, To appear in Phys. Rev. Lett. (2001