共查询到20条相似文献,搜索用时 0 毫秒
1.
A.V. Belyaev 《Journal of magnetism and magnetic materials》2010,322(17):2596-2606
We use the Langevin law of magnetization to study the linear stability of a convective flow in a flat vertical layer of ferrofluid subject to a transverse temperature gradient and a uniform magnetic field. The stability of the flow against planar, spiral and three-dimensional perturbations is examined, and the stability boundaries and characteristics of critical disturbances are determined. The competition between the monotonic mode and two types of wave modes is analyzed taking into account the properties of the fluid (magnetic susceptibility and Prandtl number) and the magnetic field strength. The domain of parameters where the oscillatory thermomagnetic wave instability exists is found. 相似文献
2.
The problem of a magnetic liquid which completely fills a vertical cylindrical cavity in an undeformable horizontal layer
of a magnet having the same magnetic properties as the liquid is considered. The entire system is immersed in a uniform vertical
magnetic field. in a linear formulation of the problem an approximate solution in the form of series is obtained for the evolution
of an initial small deviation of the free surface of the liquid from its flat equilibrium shape. An experiment is performed
which shows that the initially flat free surface takes on a stable domed shape as the field strength is increased (from zero)
and that a further increase in the field in a certain restricted range leads to the formation of an annular corrugation. The
structures observed, which are the result of the nonlinear stage in the development of the initial perturbation, are qualitatively
similar to the first two modes of the solution obtained.
Zh. Tekh. Fiz. 68, 23–30 (January 1998) 相似文献
3.
The instability and disintegration of a thin layer of a magnetic fluid in a perpendicular magnetic field are considered. New
experimental findings for the dependence of the resulting surface structure of the layer on the external magnetic field and
thickness of the layer are reported. Light diffraction by such structures is studied. Experimental data are compared with
today’s theoretical concepts. 相似文献
4.
Capillary origami is the wrapping of a usual fluid drop by a planar elastic membrane due to the interplay between capillary and elastic forces. Here, we use a drop of magnetic fluid whose shape is known to strongly depend on an applied magnetic field. We study the quasistatic and dynamical behaviors of such a magnetic capillary origami. We report the observation of an overturning instability that the origami undergoes at a critical magnetic field. This instability is triggered by an interplay between magnetic and gravitational energies in agreement with the theory presented here. Additional effects of elasticity and capillarity on this instability are also discussed. 相似文献
5.
《Superlattices and Microstructures》1998,24(3):221-226
Magnetostriction loops of a hard superconductor are calculated analytically. The geometry under consideration is a thin flat superconductor in a magnetic field perpendicular to the flat face of the sample. The analytical representation of the results is given in a relationship with the magnetic flux distribution inside a sample in the mixed state of superconductivity. The simulations are consistent with the measurements on the high-temperature superconductor LaSrCuO. 相似文献
6.
T. A. Prokopieva V. A. Danilov S. S. Kantorovich 《Journal of Experimental and Theoretical Physics》2011,113(3):435-449
Using a fine weave of theoretical analysis and computer simulations, we found various aggregates of magnetic single-domain
nanoparticles, which can form in a quasi-two-dimensional (q2D) ferrofluid layer at low temperatures. Our theoretical investigation
allowed us to obtain exact expressions and their asymptotes for the energies of each configuration. Thus, for ferrofluid q2D
layers it proved possible to identify the ground states as a function of the particle number, size, and other system parameters.
Our suggested approach can be used for the investigation of ground state structures in systems with more complex interparticle
interactions. 相似文献
7.
I. V. Marchuk 《Journal of Engineering Thermophysics》2009,18(3):227-237
In this paper, steady thermocapillary flow in a thin horizontal layer of a viscous incompressible liquid with a free surface
is considered. An axially symmetric steady problem with a localized thermal action on a horizontal liquid layer with a deformable
free surface is solved in a thin-layer approximation. In addition to the thermocapillary effect, the model takes into account
the capillary pressure caused by the free surface variable curvature and the convective mechanism of heat transfer in the
liquid. Analytical expressions for the velocity vector components as functions of the liquid layer thickness and surface temperature
are obtained. The free surface and velocity profiles caused by various kinds of heating are calculated. The influence of convective
heat transfer on the flow pattern is analyzed. 相似文献
8.
V. M. Korovin 《Technical Physics》2014,59(11):1577-1584
The Rosensweig instability induced by magnetic forces of the flat free surface of the layer of a stationary nonlinearly magnetizable ferrofluid is considered. The fluid covers a horizontal plate of a nonmagnetic material, located in a tilted magnetic field. The critical value of the vertical component of the magnetization vector is calculated in the linear formulation for a deep magnetic fluid for any physically admissible magnetization law. The influence of the horizontal component of the applied magnetic field on the onset of instability upon the modified Langevin magnetization is analyzed. 相似文献
9.
Distortions induced by an external magnetic field in the magnetic structure of a thin layer of a uniaxial collinear antiferromagnet
with rough surfaces are studied using computer simulation. It is shown that, under certain conditions, the presence of atomic
steps at the layer surfaces causes the antiferromagnetic layer to break up into domains. The character and magnitude of distortions
are found for an arbitrary ratio of the distance between atomic steps to the order parameter correlation length.
Original Russian Text ? A.I. Morosov, I.A. Morosov, A.S. Sigov, 2007, published in Fizika Tverdogo Tela, 2007, Vol. 49, No.
7, pp. 1228–1235. 相似文献
10.
V. M. Korovin 《Technical Physics》1999,44(10):1141-1149
A linear partial differential equation describing the evolution of an initial disturbance of a flat free surface of a thin
layer of a viscous magnetic fluid covering a horizontal plate in the presence of a uniform magnetic field, is derived within
a system of ferrohydrodynamic and magnetostatic equations. The effect of magnetizing the plate on the stability of the flat
free surface is investigated. An estimate is obtained for the minimum value of the tangential component of the magnetization
vector of the fluid sufficient to radically alter the pattern of the final breakup of the continuous layer.
Zh. Tekh. Fiz. 69, 14–22 (October 1999) 相似文献
11.
The instability of the charged free surface of a horizontal liquid layer heated from the solid bottom against excess electric
charge is studied theoretically for the case in which this type of instability is combined with thermal-convective instability.
The structure of the total spectrum of unstable wave flows and physical parameters influencing the structure of the spectrum
are determined. 相似文献
12.
13.
14.
The motion of a ferrofluid drop in a liquid nonmagnetic medium under the action of a rotating magnetic field is analyzed experimentally. A deviation of the falling drop from the vertical direction in the fields exceeding a certain critical value is detected. An extremum of the dependence of the deviation of the drop on the frequency of the rotating field is also observed. The results are analyzed theoretically and the algorithm of the numerical solution of the problem is proposed. 相似文献
15.
The behavior of a nonmagnetic drop suspended in a magnetic fluid and subjected to the action of a rotating magnetic field
is studied experimentally. The configurations of the drop in the form of prolate and oblate ellipsoids of revolution in the
rotating field are investigated, and disintegration of the drop in the rotating field and the development of comb instability
of its surface under certain conditions are observed. 相似文献
16.
The features of refraction (including the Goos-Hánchen effect) of a TM or TE bulk electromagnetic wave incident from outside
on the surface of a chiral magnetoelectric with the homogeneous antisymmetric magnetoelectric interaction has been analytically
studied on an example of the two-sublattice model of a multiferroic. In particular, it has been shown that the requirement
that the diagonal components of the permeability and permittivity tensors are simultaneously negative is not necessary for
the implementation of the properties of a left-handed medium. The results have been generalized to the case of an easy-axis
antiferromagnet with an antisymmetry center with the 4
z
±2
x
+
I
− structure in the static external magnetic field perpendicular to the easy axis of magnetization. Some results of this work
were preliminarily reported in D.V. Kulagin, G.G. Levchenko, A.S. Savchenko, A.S. Tarasenko, and S.V. Tarasenko, JETP Lett.
92, 511 (2010). 相似文献
17.
研究了由非磁性聚苯乙烯颗粒弥散于煤油基Fe_3O_4磁性液体中制备而成的磁性液体复合体.该复合体双折射效应和线二向色性随外磁场变化.在相同的磁场条件下,复合体的双折射效应较纯磁性液体有减弱而二向色性较后者有所增强.文中采用一简化模型对结果给出了解释. 相似文献
18.
V. M. Korovin 《Technical Physics》2010,55(9):1275-1282
A thin layer of a Newtonian magnetic fluid wetting the faced-down surface of a horizontal magnetized plate in a vertical magnetic
field is considered. The lower boundary of the layer is the interface with a stationary gas. The effect of magnetic forces
on the development of the Rayleigh-Taylor instability is considered in the linear formulation of the long-wave approximation
of ferrohydrodynamic equations. 相似文献
19.
Ultra-thin amorphous carbon (a-C) overcoats of different thicknesses were sputtered on magnetic thin-film disks. The chemistry at the interface of the carbon overcoat and the magnetic layer was studied using Angle-Resolved X-ray Photoelectron Spectroscopy (ARXPS). For a-C overcoats thinner than 20 Å, the interface was found to consist of metal carbides, metal oxides, and carbon–metal–oxygen complexes, most likely carbonyls. In marked contrast, a clean transition from metals to carbon with thin metal carbides at the interface was found for the 40 Å a-C overcoat. The evolution of the C 1s, Co 2p, Ta 4f, and O 1s spectra as a function of carbon thickness and polar angle suggests that the carbon films form in a layer-by-layer fashion. The oxygen from the ambient can diffuse through carbon films when the carbon thickness is ≤20 Å, and leads to the formation of metal oxides and carbonyls at the carbon–metal interface. Overlayer thickness of ∼40 Å effectively inhibits oxygen diffusion and thus leaves the magnetic layer fully intact. This ∼40 Å carbon thickness points to a required minimum coverage necessary to maintain a functionally viable magnetic hard disk as well as other systems that use carbon overcoats on polished metal substrates. 相似文献