Magnetic traveling-stripe forcing: Enhanced transport in the advent of the Rosensweig instability

Abstract

A new kind of contactless pumping mechanism is realized in a layer of ferrofluid via a spatiotemporally modulated magnetic field. The resulting pressure gradient leads to a liquid ramp, which is measured by means of X-rays. The transport mechanism works best if a resonance of the surface waves with the driving is achieved. The behavior can be understood semi-quantitatively by considering the magnetically influenced dispersion relation of the fluid.

Recent progress in ferrofluids research: novel applications of magnetically controllable and tunable fluids

“…[169][170][171][172] Modulation of the applied vertical magnetic eld by a traveling sinusoidal wave, generated by a conveyor belt with iron rods has been used to generate a contact less pumping mechanism on a free surface ferrouid layer in the advent of the Rosensweig instability. [173][174][175] Similarly, a rotating magnetic eld is used to move a ferrouid inside a channel with high control over direction, which depends on the magnitude and frequency of the applied eld. 176 The self sealing property of ferrouid plugs has been recently used in various types of valves, 177,178 which can be manipulated externally by permanent magnets in different arrays.…”

Material transport of a magnetizable fluid by surface perturbation

“…However, a traveling inhomogeneous magnetic field induces a traveling surface wave, which affects a flow with a nonzero flow rate inside the magnetic fluid. This phenomenon was observed in experiments [9][10][11], which created traveling waves on the surface of a magnetic fluid with a temporally and spatially varying magnetic field. Either a flow of a nonzero flow rate [9] was observed in these experiments or a sloping surface of the magnetic fluid appeared [10,11].…”

Amplitude equation for stationary convection in a rotating viscoelastic magnetic fluid

“…As a start, here we present and characterize the influence of the modulation on the layer of ferrofluid in the subcritical regime. One method of generating a spatially modulated magnetic field was described in [6,7] and uses rods of metallic iron to modulate a homogeneous magnetic field. It lacks the possibility to control the amplitude of modulation independently from the field offset, a nuisance which is overcome in the experiments presented in this paper.…”