Vortex flows induced by drop-like aggregate drift in magnetic fluids

Abstract

The paper reports a new phenomenon—vortex flows in isothermal magnetic fluids in the vicinity of the localized source of magnetic field (magnetized iron sphere) induced by the drift of drop-like aggregates. Although the observed magnetic precipitation of drop-like aggregates resembles an ordinary rainfall in the Earth atmosphere, its origin and nature are quite different. In magnetic fluids this “rain” is induced by the non-uniform magnetic field and occurs at the scale of 1 mm, not at the scale of several kilometers as in the Earth atmosphere. The reason of this phenomenon is that the applied magnetic field initiates phase transition of “gas-liquid” type which is accompanied by formation of condensed phase represented by drop-like aggregates with the characteristic dimension of about tens of micrometers elongated along the field lines. Inhomogeneous spatial distribution of drop-like aggregates leads to deviation of the ponderomotive force, which is responsible for the formation of vortex flows in the fluid. The “rain” is the primary reason for the vortex flows and it lasts until all magnetic particles capable of condensing into drop-like aggregates precipitate at the surface of the condensation core (iron sphere). Thus, vortex flows induced by drop-like aggregate magnetophoresis represent one variant of “gas-liquid” phase transition. Hydrodynamic flows intensify mass transfer in vicinity of magnetic condensation core and considerably speed it up.