•Separation of bubbles from a gas cavity in a magnetic liquid is studied.•Analysis of acoustomagnetic oscillations gives the bubble’ s radius.•The gas bubble radius does not depend on the gas influx ...rate.•Possible application as a gas counter for microfluidic devices.
In this work, we report results of the experimental study of the dynamics of a gas bubble separating from the air cavity in a magnetic fluid placed in an inhomogeneous magnetic field created by a ring magnet. Two experiments were carried out for samples with different concentrations: video recordings of the interphase boundary in a flat channel and recordings of electromagnetic vibrations caused by the gas bubble oscillations in a magnetic fluid. It is shown that the bubbles have a stable size. The respective dependencies of the bubble size on the magnetic fluid concentration and the air supply argue that it is possible to use the considered setup as a microdoser or a gas meter in microfluidics applications.
In the article, magnetization, viscosity and its increment (“magnetoviscous” effect) in a thin near-wall layer of the column of magnetic fluid that oscillates in the tube when applying a strong ...transverse magnetic field are assessed. Calculations were performed using formulae obtained on the basis of two different theoretical approaches. The described technique is of interest for studying magnetophoresis and the processes of aggregation of magnetic nanoparticles.
The findings of the experimental research of a phased air cavity capture in a flat channel with a magnetic fluid located along the axis of the annular magnet influenced by the changing in sign ...magnetic field are discussed. The research was carried out with four magnetic fluids with the magnetic phase concentrations of 1.93%; 2.70%; 4.34%; 9.08%. The analysis of the obtained results is presented within the framework of the electrodynamic model of “low magnetic bodies” based on the development of the system of isolines of the module of the magnetic field intensity. The provided data, first, clarify the conclusions of the previous interpretation of the air cavity capture with an opaque magnetic fluid column, and second, can be useful to solve practical issues of microhydraulics.
A study is performed of the detachment of bubbles from a gas cavity in a uniform magnetic field inside a vertical channel filled with a magnetic fluid. The behavior of the air–magnetic fluid ...interface during detachment is considered. Dependences are given for the size of the detached bubbles on the configuration of the magnetic field, the concentration of the magnetic fluid, and the thickness of the channel.
In this work, we present a measurement system based on the thin layer of magnetic fluid aimed at scanning either the non-uniform magnetic field distribution applicable for magnetic levitation systems ...(MagLev) or determining small excess gas pressure. The key idea is based on the photo registration of a transparent air-filled cavity formed in a thin magnetic fluid layer due to balancing the gas pressure and the pressure emerging due to magnetic forces. As a result, the contour of the magnetic field lines in 3D space is visible. It is shown that the theoretical analysis and numerical simulations are consistent with experimental results.
Abstract
The dynamics of some magnetic fluid (MF) samples of various concentrations filling the tube horizontally and held by a field of a magnetic axial system made based on unipolar permanent ...rare-earth ring magnets were studied. The magnetic field of an “axial” magnetic system of MSO was studied, as well as the dependence of the system oscillation frequency on the length of the MF cylinder. An original method for determining MF magnetization is proposed and applied to the obtained data. Magnetization was determined for three magnetic fluid samples. The results obtained by the developed method are comparable to the magnetization values obtained by the ballistic method. The developed and presented technique of a dynamic experiment with measuring oscillations frequency of the “MF column suspended in a strong and inhomogeneous magnetic field” system involves the creation of a new absolute method for determining saturation magnetization and can be useful for studying magnetophoresis and aggregation processes of magnetic nanoparticles. This technique is used to study the degree of elastomagnetic consistency parameters over time.
Magnetic, acoustic, and thermophysical phenomena in magnetic fluid systems have found application in the design of magnetic fluid seals, shock absorbers, sensitive three-axis accelerometers, density ...meters, and a number of other advanced devices. This explains the interest in studying these effects. Lately, due to the rapid development of microfluidics, more and more works have appeared that deal with magnetic fluid dynamics in channels of various shapes when various external physical fields affect them. However, several aspects have only been studied superficially, although they are potentially of great scientific and practical interest; these are levitating gas cavity properties and magnetic, acoustic and thermophysical phenomena accompanying dynamic gas cavity and bubble displacement in a magnetic fluid. This paper investigates the dynamics of bubble trapping in magnetic fluid located in the so-called magnetic vacuum region of an annular magnet. We obtained data on effects of centrifugation and magnetic fluid structure on the strength of magnetic fluid bridges subjected to external pressure. This information may be useful for developing a test bench for magnetic fluids used in seals, where fluids undergo similar effects. We used two samples of magnetic fluid to perform an experiment which involved compressing the air cavity, eventually leading to gas bubbles detaching from the samples. We draw conclusions concerning the effects of physical parameters of magnetic fluids and magnetic field configuration on the diameter of the resulting bubbles.
Results are presented from studying the dynamics of gas bubbles injected into a ferrofluid under the influence of an inhomogeneous magnetic field in microchannels of five configurations. The ...dependences of bubble sizes on the configuration of the magnetic field and the physical properties of the magnetic fluid are obtained. These results can be used in gas meters and dispensers in microfluidics.
Measurements and theoretical analysis of the processes of static displacement and oscillations of the magnetic fluid column confined by magnetic levitation in a strong magnetic field in a ...horizontally placed tube are carried out. The calculations of the saturation magnetization, made on the basis of the obtained results of the displacement and the oscillation frequency for the sample of the magnetic fluid under study, are in good agreement with the experimental data. The described technique is of interest when studying saturation magnetization, magnetophoresis, aggregation of nanoparticles and their temporal dependence in magnetic colloids.
An experimental setup is developed for studying magnetophoresis in a layer of a magnetic fluid several millimeters thick by the method of light transmission and reflection. The region of the ...sign-alternating magnetic field of a ring magnet is used in the experiment. The clarification of the central portion of the magnetic fluid layer, observed for several days, is interpreted by the fact that the particle concentration is redistributed due to the processes of magnetophoresis of microparticles and diffusion of nanoparticles in an inhomogeneous magnetic field.
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