Experimental investigation of surface instability of a thin layer of a magnetic fluid

Abstract

In the present work the instability of a flat horizontal thin layer of a magnetic fluid (the depth of no more than 50 µm) under the action of a uniform magnetic field is studied experimentally. It was revealed that the development of instability under the action of tilted magnetic field can lead to the formation of parallel ridges on a fluid surface; the ridges undergo a transformation into hexagonal system of conical peaks with the magnetic field increasing. The necessary conditions for the formation of these surface patterns are studied. It was found that the development of instability of quite thin layers may result in layers breakup. The dependencies of instability wave number on the system physical parameters are obtained. The time for the development of instability is measured. The experimental results are compared with the existing theory and discussed.

Instability of the miscible magnetic/non-magnetic fluid interface

“…The last assumption is confirmed by the results of Cebers (1997), who for a close problem showed that smearing of the diffusion front shifts the most dangerous mode to a longer wavelength. The result obtained rather resembles the behaviour of the free interface of a magnetic fluid, on which the Rosensweig instability (Cowley & Rosensweig 1967) develops upon instantaneous switching on of a magnetic field of various magnitudes (Bashtovoi, Krakov & Reks 1985; Dikansky, Zakinyan & Mkrtchyan 2010; Zakinyan, Mkrtchyan & Dikansky 2016). With an increase in the value of the switched-on magnetic field, the length of the most rapidly developing wavelength in this case significantly decreased.…”

“…This result was consistent with the linear theory, in which the dispersion equation is determined by both the magnitude of the magnetic field and the surface tension and thickness of the magnetic fluid layer. However, in the problem considered in this paper, there is no surface tension, so that direct analogies with the results of Bashtovoi et al (1985), Dikansky et al (2010) and Zakinyan et al (2016) are impossible. We will return to the discussion of this analogy below.…”

“…2010; Zakinyan et al. 2016), this dependence also has a decreasing character. The presented result is in agreement with the simulation data shown in figure 11.…”

“…(2010) and Zakinyan et al. (2016) are impossible. We will return to the discussion of this analogy below.…”

Damping Force Modeling and Suppression of Self-Excited Vibration due to Magnetic Fluids Applied in the Torque Motor of a Hydraulic Servovalve

“…Manukyan et al [18] compared the wetting characteristics of an oil-based ferrofluid and a water-based magnetic paint on a hydrophobic flat surface. For the application in vibration absorbers and dampers, it is essential to investigate the mechanical properties of magnetic fluids [19][20][21]. Hayashi et al [22] studied the resistance force of a shock absorber due to magnetic functional fluids containing both micrometer-sized and nanometer-sized magnetic particles.…”