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1.
The elongation of a ferroelastic material sample (whose initial shape is a sphere or an ellipsoid of revolution) under the
action of an external magnetic field is studied in an in approximation of small strains. For a sphere, there is a classical
estimate obtained under the assumption that elongating in the direction of the field, it becomes a spheroid and the stress
and strain fields remain uniform. In the present calculation, it is assumed that the body is an ellipsoid (a sphere in a particular
case) only in the absence of an external field; the shape of the sample in the presence of a field is not specified in advance
but is found from the condition of balance of surface forces (elastic and magnetic). For the spherical case, the problem is
solved exactly: it is shown, that the contour of the deformed body is described by a third-order algebraic equation. The case
where the initial configuration is an ellipsoid of revolution is studied numerically. It is shown that in all versions, the
refined solution leads to an appreciable increase in the elongation of the sample compared to the classical estimate.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 3, pp. 153–164, May–June, 2005. 相似文献
2.
The nonlinear convective instability of a plane horizontal conducting fluid layer placed in a uniform vertical magnetic field
is studied [1]. A similar problem was previously considered in [2] but with allowance only for so-called weakly nonlinear
third-order effects. In the present paper attention is concentrated on the study of the finite-amplitude instability mechanisms
associated with the "hard" excitation of vibrations.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 23–28, January–February,
1998. 相似文献
3.
A new type of flow in a magnetic fluid has been experimentally detected and investigated. The interaction between an alternating
nonuniform magnetic field and a magnetic fluid leads to the parametric excitation of traveling capillary-gravitational waves
which are the direct cause of the average flow. A necessary condition of formation of hydrodynamic flows in an alternating
field is also the presence of time-dependent harmonics with multiple frequencies synchronized with the first harmonic, so
that the time dependence of the ponderomotive force is generally pulsed. It is shown that for plane vibrational flows the
classical theory cannot explain the high intensity of the average flows observed. It is suggested that the high intensity
of magnetovibrational flows is related to the violation of the cylindrical symmetry of the traveling capillary-gravitational
waves and the transition to a three-dimensional motion.
Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 124–133, January–February,
1998. 相似文献
4.
A. V. Proskurin A. M. Sagalakov 《Journal of Applied Mechanics and Technical Physics》2008,49(3):383-390
The stability of the plane flow of an electrically conducting fluid with respect to small perturbations was studied at large
Reynolds numbers in the presence of a longitudinal magnetic field. The dependence of the critical Reynolds number on the electrical
conductivity is investigated. At large Reynolds numbers, a new branch of instability and a sudden change in the critical Reynolds
numbers is found.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 45–53, May–June, 2008. 相似文献
5.
Chyong Za Bin' 《Fluid Dynamics》1986,21(6):934-939
A phenomenological theory is proposed to describe the equilibrium of a thin structured film of magnetic fluid on the surface
of another non-magnetic fluid in the absence of an external magnetic field. The stability of a semi-infinite plane magnetic
film is considered on the basis of the theory proposed. The result obtained can serve as a qualitative explanation of experiments
performed on thin films of magnetic fluid.
Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 105–110, November–December, 1986.
The author is grateful to L. I. Sedov and V. V. Gogosov for useful discussions and their interest in his work. 相似文献
6.
The development of the tearing instability is studied in the presence of a high toroidal magnetic field and a high plasma
conductivity. The variation of the plasma density is shown to be significant in this case.
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 2, pp. 3–9, March–April, 1998. 相似文献
7.
The stability of an axisymmetric thermocapillary flow driven by a point heat source located in the neighborhood of the free
surface of a fluid filling a deep tank is investigated theoretically and experimentally. It is shown that for certain values
of the depth and power of the heat source thermocapillary convection becomes unstable with respect to oscillating perturbations
of the surface shape.
Perm’, Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 92–103, March–April, 2000. 相似文献
8.
The process of quenching cylindrical steel specimens in a magnetic fluid in the presence of a magnetic field is investigated. It is shown that depending on the strength of the magnetic field and its orientation with respect to the surface of the cylinder, local vapor formations that result in nonuniform cooling may appear on the surface and that the boiling of the fluid on the surface may take place in different regimes. The processes of formation of local vapor films were experimentally modeled by observing the shape of the surface of the magnetic fluid surrounding a cylinder placed between the poles of an electromagnet. An equation describing the shape of the free surface of the magnetic fluid and the evolution of the air pockets with variation of the volume of magnetic fluid and the strength of the magnetic field is derived. The surface shape of the magnetic fluid calculated from the theory proposed is shown to be in good agreement with the experimental data.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 3–11, March–April, 1989. 相似文献
9.
Parametric convective instability of a horizontal layer of a homogeneous ferrofluid under the action of an alternating magnetic
field is studied. A case with rigid boundaries is considered. Convection thresholds are found. In an alternating magnetic
field with a zero mean value, perturbations are found to have a synchronous character. These perturbations, however, can belong
to different classes, because they depend on the temperature difference on the layer boundaries, the layer thickness, the
frequency and amplitude of the alternating external field, and the physical properties of the ferrofluid.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 18–27, July–August, 2009. 相似文献
10.
The electrothermoconvective instability of a plane horizontal layer of weakly conducting fluid in a modulated vertical electric
field is investigated. The analysis is based on the electrohydrodynamic approximation. The stability threshold in the linear
approximation is found using Floquet’s theory. The effect of periodic modulation on the fluid behavior is studied in both
the presence and the absence of the constant component of the electric field. It is shown that modulation can stabilize the
unstable ground state or destabilize fluid equilibrium, depending on the amplitude and frequency. In addition to a synchronous
or subharmonic response to an external forcing, the instability may be associated with two-frequency (quasiperiodic) perturbations.
The cases of weightlessness and a transversely stratified fluid in a static gravity field are considered.
Madrid, Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 31–38, May–June,
2000.
The investigations whose results are presented in this paper were supported by the Russian Foundation for Basic Research (project
No. 98-01-00507). 相似文献
11.
The stability of the interface between two immiscible fluids of different density which occupy a plane horizontal layer performing
harmonic horizontal oscillations is considered. Within the framework of the ideal fluid model a transformation reducing the
problem of small plane perturbations to the Mathieu equation is found. Resonance instability domains associated with the formation
of capillary-gravitational waves are investigated. A model which takes into account dissipation processes due to the presence
of viscous friction is constructed. The role of the viscous dissipation in suppressing resonance instability is discussed.
Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 25–31, May–June, 1998.
The work was carried out with partial support from the Russian Foundation for Basic Research (project No. 95-01-00386). 相似文献
12.
Marie-Charlotte Renoult Rolfe G. Petschek Charles Rosenblatt Pierre Carlès 《Experiments in fluids》2011,51(4):1073-1083
Shaping arbitrary fluid interfaces opens interesting perspectives for fluid-based processes and experiments. We demonstrate
an experimental method to create non-planar static interfaces of almost arbitrary shape between two fluids, one of which is
made highly magnetically permeable by the addition of a magnetic compound. By relying on spatially modulated magnetic fields,
a non-homogeneous magnetic force is added to Earth's gravitational force, and a non-planar static interface can be stabilized.
Precision experimental measurements are possible because we have developed a general method that allows us to predict numerically
the shape of the interface, thereby facilitating the optimal experimental design before actually implementing it. As a first
example, we apply this method to the Rayleigh–Taylor instability between two immiscible fluids. The results we obtain demonstrate
the feasibility of the experimental method and the accuracy of the numerical predictions. 相似文献
13.
The two-dimensional thermal convection of a elasticoviscous fluid in a horizontal cylinder with a square cross-section heated
from below is investigated. For describing the rheological properties of the fluid the Oldroyd model with the upper convective
derivative is used. The investigation is carried out numerically using the finite-difference method. The instability limits
of mechanical equilibrium with respect to monotonic and oscillatory perturbations are determined. Supercritical convection
regimes are investigated numerically.
Perm. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 5–11, July–August, 2000.
This work was carried out with financial support from the Program of State Financial Support for Leading Science Schools (grant
No. 96-15-96084). 相似文献
14.
D. A. Pelevina 《Fluid Dynamics》2016,51(6):722-732
The shape of the surface of a magnetic fluid containing a cylindrical body made of a well-magnetizable material (magnetic field concentrator) in a uniform applied magnetic field is studied experimentally and theoretically. Various static shapes of the surface are calculated numerically taking into account the gravity forces, the surface tension, and the dependence of the magnetic fluid magnetization on the magnetic field strength. It is found that there exists several equilibrium shapes of the magnetic fluid surface. Abrupt changes in the magnetic fluid surface and its hysteresis are predicted theoretically and observed experimentally. The theoretical and experimental results are compared. 相似文献
15.
Using a counter rotating parallel plate shear flow cell, the shape relaxation of deformed droplets in a quiescent matrix is
studied microscopically. Both the effects of geometrical confinement and component viscoelasticity are systematically explored
at viscosity ratios of 0.45 and 1.5. The flow conditions are varied from a rather low to a nearly critical Ca number. Under
all conditions investigated, viscoelasticity of the droplet phase has no influence on shape relaxation, whereas matrix viscoelasticity
and geometrical confinement result in a slower droplet retraction. Up to high confinement ratios, the relaxation curves for
ellipsoidal droplets can be superposed onto a master curve. Confined droplets with a sigmoidal shape relax in two stages:
the first consists of a shape change to an ellipsoid with a limited amount of retraction, and the second is the retraction
of this ellipsoid. The latter stage can be described by means of one single relaxation time that can be obtained from the
relaxation of initially ellipsoidal droplets. The experimental results are compared to the predictions of a recently published
phenomenological model for droplet dynamics in confined systems with viscoelastic components (Minale et al., Langmuir 26:126–132,
2010). However, whereas the model predicts additive effects of geometrical confinement and component viscoelasticity, the experimental
data reveal more complex interactions. 相似文献
16.
The processes of interaction between concentrated energy fluxes and solid targets have been investigated in a number of studies.
The generation of magnetic fields in erosional plasma formations has been experimentally observed [1–4]. However, the evolution
of magnetic fields in plasma jets has not yet been studied in sufficient detail. This paper is devoted to a numerical investigation
of unsteady three-dimensional erosion plasma flows and the generation in those flows of magnetic fields resulting from the
action of laser radiation on solid targets.
Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 135–140, November–December, 1986.
The authors are grateful to I. V. Nemchinov and B. T. Fedyushin for useful discussion of their results. 相似文献
17.
The dynamics of a rigid cylindrical body subjected to high-frequency rotational vibration about its own axis in a liquid-filled
sector of a horizontal cylindrical layer are investigated experimentally and theoretically. It is found that the vibrations
generate an average force on the body which in the case of a body denser than the fluid is directed toward the axis of rotation.
Under certain conditions this force exceeds the gravity force, causing the body to float. This effect is analyzed theoretically
in the high-frequency low-amplitude vibration approximation. It is shown that the force detected acts on the body over the
entire fluid volume.
Perm’. Paris. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 29–39, July–August,
1998.
The work partially supported by the Russian Foundation for Basic Research (project No. 96-01-00932) and Grant No. 920-5208/95
of the US National Aviation and Space Administration (US NASA). 相似文献
18.
The flow of a three-dimensional sheet on a curved wall is considered. Gravity and surface tension forces act on the sheet
while a droplet stream falls on its free surface. The systems of equations of viscous incompressible fluid dynamics on a curved
rigid surface and the boundary conditions with allowance for the falling droplet stream are formulated. The problems of steady
axisymmetric motion of the sheet on cylindrical and conical surfaces are considered. The effect of the curvature of the rigid
wall on the solution is examined.
Kharkov. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 42–50, July–August, 1994. 相似文献
19.
E. Movahednejad F. Ommi S. M. Hosseinalipour C. P. Chen S. A. Mahdavi 《Heat and Mass Transfer》2011,47(12):1591-1600
This paper describes the implementation of the instability analysis of wave growth on liquid jet surface, and maximum entropy
principle (MEP) for prediction of droplet diameter distribution in primary breakup region. The early stage of the primary
breakup, which contains the growth of wave on liquid–gas interface, is deterministic; whereas the droplet formation stage
at the end of primary breakup is random and stochastic. The stage of droplet formation after the liquid bulk breakup can be
modeled by statistical means based on the maximum entropy principle. The MEP provides a formulation that predicts the atomization
process while satisfying constraint equations based on conservations of mass, momentum and energy. The deterministic aspect
considers the instability of wave motion on jet surface before the liquid bulk breakup using the linear instability analysis,
which provides information of the maximum growth rate and corresponding wavelength of instabilities in breakup zone. The two
sub-models are coupled together using momentum source term and mean diameter of droplets. This model is also capable of considering
drag force on droplets through gas–liquid interaction. The predicted results compared favorably with the experimentally measured
droplet size distributions for hollow-cone sprays. 相似文献
20.
A method of solving the problem of the motion of a cylinder of given shape below the free surface of an infinitely deep heavy
fluid is perfected for large Froude numbers. The motion of a circular cylinder is investigated at small distances from the
free surface. Solutions of the problem are given for cylinders with noncircular cross-sections.
Kazan. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 34–45, July–August, 2000.
The work was carried out with financial support from the Russian Foundation for Basic Research (projects Nos. 99-01-00169
and 99-01-00173). 相似文献