Ferrohydrodynamics: testing a third 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 third 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.