“Wall Viscosity” of Magnetic Fluid Oscillations in a Strong Magnetic Field

Resumo

The authors provide an estimation of the “wall viscosity” and its increment (“magneto-viscous” effect) in a thin near-wall layer of a column of magnetic fluid oscillating in the tube when a strong transverse magnetic field is applied. The calculation is performed according to the formula obtained on the basis of two different theoretical approaches and applied to the previously published experimental results of the complex measurement of oscillation frequency and saturation magnetization of the magnetic fluid. These results are commented upon, stemming from the assumed absence of the field dependence of viscosity. The estimates of “wall viscosity” “from above” and “from below” are used to calculate their contribution to the damping coefficient of oscillations.