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Arthur Zakinyan

Publications and source records attributed to Arthur Zakinyan.

10 recordsLinked to original sources
arXiv2017

Flows and Instabilities of Ferrofluids at the Microscale

In the present work we report on the behavior of ferrofluid microdrops in an immiscible nonmagnetic carrier fluid and vice versa subjected to the action of magnetic fields. Our experiments evidence previously unexplored instability and flow patterns. We investigated the instabilities initiated by constant magnetic field and by combined action of constant and rotating magnetic fields. The observed instabilities lead to the formation of various microdrop configurations such as star-like and comb-like shapes, bending deformation, ridges and crests, spiral arms and rings, etc. The reviled peculiarities of the microscopic drops behavior can be of interest in applications to the ferrofluid-based microfluidics.

cond-mat.soft↗
arXiv2017

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

In the present work the instability of a flat horizontal thin layer of a magnetic fluid (the depth of no more than 50 \mum) 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.

physics.flu-dyn↗
arXiv2017

Ferrofluid Capillary Rise in Porous Medium under the Action of Non-Uniform Magnetic Field

The capillary flow of a ferrofluid in a single cylindrical capillary tube and through a sandy porous medium under the action of a non-uniform magnetic field is studied experimentally. The dynamics of the capillary rise and the static case have been considered. It has been shown that the non-uniform magnetic field with upward directed gradient accelerates the capillary rise; contrary, the non-uniform magnetic field with downward directed gradient decelerates the capillary rise. Time dependences of the ferrofluid height and maximum reachable height of ferrofluid have been analyzed. The method of the study of ferrofluid capillary rise based on the use of magnetic measurements has been proposed. It has been demonstrated that porous material parameters can be extracted from the results of measurements of the inductances of the solenoid with porous medium inside and the small sensing coil within a single experiment.

physics.flu-dyn↗
arXiv2014

Electrical properties of chain microstructure magnetic emulsions in magnetic field

The work deals with the experimental study of the emulsion whose dispersion medium is a magnetic fluid while the disperse phase is formed by a glycerin-water mixture. It is demonstrated that under effect of a magnetic field chain aggregates form from the disperse phase drops. Such emulsion microstructure change affects its macroscopic properties. The emulsion dielectric permeability and specific electrical conductivity have been measured. It is demonstrated that under the effect of relatively weak external magnetic fields (~ 1 kA/m) the emulsion electrical parameters may change several fold. The work theoretically analyzes the discovered regularities of the emulsion electrical properties.

cond-mat.soft↗
arXiv2013

Electrocapillary instability of magnetic fluid peak

The paper presents an experimental study of the capillary electrostatic instability occurring under effect of a constant electric field on a magnetic fluid individual peak. The peaks under study occur at disintegration of a magnetic fluid layer applied on a flat electrode surface under effect of a perpendicular magnetic field. The electrocapillary instability shows itself as an emission of charged drops jets from the peak point in direction of the opposing electrode. The charged drops emission repeats periodically and results in the peak shape pulsations. It is shown that a magnetic field affects the electrocapillary instability occurrence regularities and can stimulate its development. The critical electric and magnetic field strengths at which the instability occurs have been measured; their dependence on the peak size is shown. The hysteresis in the system has been studied; it consists in that the charged drops emission stops at a lesser electric (or magnetic) field strength than that of the initial occurrence. The peak pulsations frequency depending on the magnetic and electric field strengths and on the peak size has been measured.

physics.flu-dyn↗
arXiv2012

Dynamics of a dielectric droplet suspended in a magnetic fluid in electric and magnetic fields

The behavior of a microdrop of dielectric liquid suspended in a magnetic fluid and exposed to the action of electric and magnetic fields is studied experimentally. With increasing electric field, the deformation of droplets into oblate ellipsoid, toroid and curved toroid was observed. At the further increase in the electric field, the bursting of droplets was also revealed. The electrorotation of deformed droplets was observed and investigated. The influence of an additional magnetic field on the droplet dynamics was studied. The main features of the droplet dynamics were interpreted and theoretically examined.

cond-mat.soft↗
arXiv2012

Motion of a deformable drop of magnetic fluid on a solid surface in a rotating magnetic field

The behavior of a magnetic fluid drop lying on a solid horizontal surface and surrounded by a nonmagnetic liquid under the action of a uniform magnetic field which is rotating in a vertical plane with low frequency (of the order of 1 Hz) has been investigated experimentally. Shape deformation and translatory motion of the drop were observed and studied. The drop translation velocity for different field amplitudes and field frequencies has been measured.

cond-mat.soft↗
arXiv2011

Drops deformation and magnetic permeability of a ferrofluid emulsion

In the paper the novel soft magnetic composite system is investigated. A ferrofluid emulsion studied demonstrates the strong magnetic properties which are atypical for commonly known emulsions. Interaction of ferrofluid emulsions with a magnetic field is considered. Structural transformations in these media, such as deformation of emulsion microdroplets and emulsion inversion, are studied. The changes in the relative permeability of emulsion associated with structural transformations are investigated. The theory of the observed phenomena is developed, and the feasibility of effectively controlling the magnetic properties of ferrofluid emulsions by applying a magnetic field is demonstrated.

cond-mat.soft↗