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1.
The problem of determination of sediment discharge by a turbulent flow of a fluid above an eroded surface of an arbitrary
relief with a finite slope of the bottom is considered. The surface of the bottom separates a stationary granular medium (sand)
from a moving two-phase mixture of a fluid and solid particles. The medium is set into motion under the action of shear stress
of the fluid. The medium obeys Coulomb's friction law for a granular medium and Prandtl's law of turbulent friction of the
fluid. As a result of solving the boundary-value problem for the motion of a two-phase mixture of a fluid and solid particles,
a generic formula for sediment discharges is derived. The sediment-discharge vector is expressed through the vector of shear
stress on the bottom, the vector of the slope of the bottom, and the distribution function of the solid particles in the bottom
layer for an arbitrary relief of the bottom with a finite slope. It is shown that the sediment discharge depends weakly on
the detailed distribution of particles in the bottom layer. Conditions of failure of the bottom surface are obtained. The
sediment-discharge formula allows one to derive a closed system of equations that determines the process of bottom erosion
in the river or channel bed.
Institute Problems of Mechanics, Russian Academy of Sciences, Moscow 117526. Translated from Prikladnaya Mekhanika i Tekhnicheskaya
Fizika, Vol. 41, No. 2, pp. 102–112, March–April, 2000. 相似文献
2.
G. Sh. Boltachev N. B. Volkov V. V. Ivanov S. N. Paranin 《Journal of Applied Mechanics and Technical Physics》2008,49(2):336-339
A model for dynamic compaction of granular medium is proposed for the case in which the external action far exceeds the yield
strength of the material. A radial axisymmetric compaction problem is solved for a granular medium with nanosize structure
in the presence of a rigid rod at the symmetry axis. Simulated data are compared with experimental data on magnetic pulsed
compaction of oxide nanopowders.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 2, pp. 211–215, March–April, 2008. 相似文献
3.
We study a 2 × 2 system of balance laws that describes the evolution of a granular material (avalanche) flowing downhill.
The original model was proposed by Hadeler and Kuttler (Granul Matter 2:9–18, 1999). The Cauchy problem for this system has
been studied by the authors in recent papers (Amadori and Shen in Commun Partial Differ Equ 34:1003–1040, 2009; Shen in J
Math Anal Appl 339:828–838, 2008). In this paper, we first consider an initial-boundary value problem. The boundary condition
is given by the flow of the incoming material. For this problem we prove the global existence of BV solutions for a suitable
class of data, with bounded but possibly large total variations. We then study the “slow erosion (or deposition) limit”. We
show that, if the thickness of the moving layer remains small, then the profile of the standing layer depends only on the
total mass of the avalanche flowing downhill, not on the time-law describing the rate at which the material slides down. More
precisely, in the limit as the thickness of the moving layer tends to zero, the slope of the mountain is provided by an entropy
solution to a scalar integro-differential conservation law. 相似文献
4.
Yu. A. Berezin L. A. Spodareva 《Journal of Applied Mechanics and Technical Physics》1998,39(6):918-921
The stability of a layer of a granular medium on an inclined plane has been studied within the framework of the model of a
non-Newtonian fluid with an index of 2, which ensures the experimentally found quadratic dependence of the shear stress on
the shear rate. It is shown analytically and numerically that these flows are stable or unstable depending on the value of
the generalized Reynolds number relative to the critical value equal to5 cot α.
Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated
from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 113–117, November–December, 1998. 相似文献
5.
V. D. Bondar’ 《Journal of Applied Mechanics and Technical Physics》2009,50(2):352-359
The plane strain of an incompressible body is studied with geometrical and physical nonlinearity and potential forces taken
into account. A nonlinear system of equations for strains is obtained in actual variables, and conditions of its ellipticity
are derived in terms of the elastic potential. Boundary conditions for strains are found from specified loads. Analytical
solutions of the boundary problem in strains and their corresponding stress fields are found for the case of identical elongations.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 217–225, March–April, 2009 相似文献
6.
G. Sh. Boltachev N. B. Volkov 《Journal of Applied Mechanics and Technical Physics》2008,49(6):1040-1046
The previously developed continual approximation is used to analyze the radial axisymmetric compaction of a granular medium
in the presence of a rigid undeformable rod on the symmetry axis. It is shown that, during pulsed loading, high densities
close to those corresponding to the nonporous state can be attained due to inertia effects. The influence of the initial radial
dimensions of the rod-powder-medium system on the compaction process is analyzed. The problem is found to be scale invariant
under various constraints imposed on the ratio of the characteristic dimensions.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 181–189, November–December, 2008 相似文献
7.
A. A. Pan’kov 《Journal of Applied Mechanics and Technical Physics》1999,40(3):523-526
The problem of predicting the effective elastic properties of composites with prescribed random location and radius variation
in spherical inclusions is solved using the generalized self-consistent method. The problem is reduced to the solution of
the averaged boundary-value problem of the theory of elasticity for a single inclusion with an inhomogeneous transition layer
in a medium with desired effective elastic properties. A numerical analysis of the effective properties of a composite with
rigid spherical inclusions and a composite with spherical pores is carried out. The results are compared with the known solution
for the periodic structure and with the solutions obtained by the standard self-consistent methods.
Perm’ State Technical University, Perm’ 614600. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No.
3, pp. 186–190, May–June, 1999. 相似文献
8.
9.
The dynamics of a granular medium in a cavity filled with incompressible viscous fluid under harmonic vertical vibration are
studied experimentally. The sand is fluidized in a relatively thin sublayer of the granular layer near the interface between
the media. The fluidization is of the threshold type and is accompanied by intense parametric oscillations of the interface.
For viscous fluids, the transition of the sand from a quasi-solid to a fluidized state and the reverse transition associated
with a decrease in the oscillation rate occur with hysteresis. The nondimensional governing parameters determining the sand
dynamics are established. The analysis is focused on the case of low nondimensional frequencies.
Perm’, Paris. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 113–122, May–June,
2000. 相似文献
10.
L. V. Baev 《Journal of Applied Mechanics and Technical Physics》2009,50(4):691-697
A problem of propagation of longitudinal and transverse waves in a multimodulus elastic isotropic medium is considered. In
the model used, the medium is described by a potential depending on three invariants of strains, which allows the influence
of preliminary deformation of the medium on the longitudinal and transverse velocities to be taken into account.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 176–182, July–August, 2009. 相似文献
11.
The Galerkin–Bubnov method with global approximations is used to find approximate solutions to initial–boundary-value creep
problems. It is shown that this approach allows obtaining solutions available in the literature. The features of how the solutions
of initial–boundary-value problems for oneand three-dimensional models are found are analyzed. The approximate solutions found
by the Galerkin–Bubnov method with global approximations is shown to be invariant to the form of the equations of the initial–boundary-value
problem. It is established that solutions of initial–boundary-value creep problems can be classified according to the form
of operators in the mathematical problem formulation 相似文献
12.
Certain aspects of wave propagation and the dynamic reaction of a granular material when subjected to a long-duration impulse
load are studied. In the majority of studies published on this subject the unsteady pressure behavior at the end-wall covered
by a layer of granular material was observed and documented. However, up to now little attention was given to explaining the
physical mechanism of this process.
Experimental results, obtained in the course of this study, regarding the pressure fields inside granular layers of different
materials, clearly show that the compaction effect strongly depends on the characteristics of the medium. This phenomenon
manifests itself by changing the gas-particle interaction in the course of the gas filtration, and by variation in the contribution
of the different forces and effective stress, σ, to the energy exchange between the gas, the particles and the shock-tube
wall.
The material permeability, f, the relative density, ν, and the particle response time, τ
p
, are the most important parameters affecting the stress formation at the end-wall covered by the granular layer. In addition
to the effect of the material parameters, the effective stress, σ, was found to strongly depend on the granular layer height,
h.
Based on detailed pressure measurements a qualitative analysis regarding the role of the particle rearrangement in the formation
of the unsteady peak at the end-wall was performed. The phenomenology of the particle–particle interaction includes rotation
and consolidation of the granules and movement or sliding of particle planes within the layer over each other. Most of these
processes are frictional in their nature. They are related to the energy losses and affect the profile and magnitude of the
compressive stress as measured at the shock-tube end-wall covered by the granular layer.
Received: 10 June 1996/Accepted: 15 October 1996 相似文献
13.
Dambaru Bhatta Mallikarjunaiah S. Muddamallappa Daniel N. Riahi 《Transport in Porous Media》2010,82(2):385-399
This present study considers the problem of steady magneto-convection in a horizontal mushy layer with variable permeability
and an impermeable mush–liquid interface during directional solidification of binary alloys. We model the flow by introducing
a uniform magnetic field in the mushy layer which is considered as a porous medium where Darcy’s law holds and the permeability
is a function of the local solid volume fraction. Basic-state solutions are obtained analytically using the no-flow condition.
With the help of multiple shooting techniques, we obtain numerical solutions to the linear perturbation system for non-magnetic
and magnetic cases. Numerical results are presented showing the effects of the magnetic field and the permeability of the
layer. These results demonstrate that the application of an external magnetic field has stabilizing effects on the convection
and can reduce the tendency for chimney formation in the mushy layer. In addition, variable permeability, which corresponds
to an active mushy layer, indicates more stable and realizable flow system as compared to the case of constant permeability. 相似文献
14.
N. V. Smelova 《Fluid Dynamics》1997,32(1):79-85
A solution of the problem of supersonic flow past a wavy wall with an adjacent subsonic layer is obtained. The solution is
a generalization of the well-known solutions [1] of the linear problem of purely subsonic and purely supersonic flow past
a wavy wall and goes over into these solutions in the limiting cases of infinite and zero wall-layer thickness, respectively.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 97–103, January–February,
1997. 相似文献
15.
The effects of viscous dissipation on unsteady free convection from an isothermal vertical flat plate in a fluid saturated
porous medium are examined numerically. The Darcy–Brinkman–Forchheimer model is employed to describe the flow field. A new
model of viscous dissipation is used for the Darcy–Brinkman–Forchheimer model of porous media. The simultaneous development
of the momentum and thermal boundary layers are obtained by using a finite difference method. Boundary layer and Boussinesq
approximation have been incorporated. Numerical calculations are carried out for various parameters entering into the problem.
Velocity and temperature profiles as well as local friction factor and local Nusselt number are shown graphically. It is found
that as time approaches infinity, the values of friction factor and heat transfer coefficient approach steady state. 相似文献
16.
A. N. Golubyatnikov 《Fluid Dynamics》1998,33(4):612-617
Within the framework of the Newtonian mechanics, we studied the possibility of the formation of a uniformly expanding gravitating
gas due to the passage of a detonation wave through a freely compressible medium (dust). The formulation of the problem is
associated with the modeling of the large-scale expansion of the Universe. At the same time, the results obtained can also
be applied to the calculation of the consequences of the spherical collapse of other gaseous masses. A class of exact solutions
taking the pressure gradient into account is derived. Possible changes in the system behavior, as compared to with case of
uniform pressure studied in [1], are analyzed.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 176–182, July–August, 1998.
The study was carried out with the support of the Russian Foundation for Basic Research (project No. 97-01-00196). 相似文献
17.
N. V. Khusnutdinova 《Journal of Applied Mechanics and Technical Physics》2008,49(4):548-552
A problem is considered for the system describing gas flows with plate boundary layer separation in Mises variables in boundary-layer
theory. The existence of generalized solutions of the problem is proved.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 36–41, July–August, 2008. 相似文献
18.
Experimental studies were made of the state behind a shock wave arising in front of a pulse jet in formation, and the development
of the vortex structure of the jet itself. A comparison was made of the experimental axial density distribution in the jet
in the region between the front of the gas and the primary shock wave with the solutions to the problem of an expanding spherical
piston and the nonself-similar problem of a point explosion.
Moscow Translated from Izvestiya, Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 146–150, September–October, 1988. 相似文献
19.
V. Sh. Shagapov M. K. Khasanov N. G. Musakaev 《Journal of Applied Mechanics and Technical Physics》2008,49(3):462-472
Specific features of formation of gas hydrates due to injection of a gas into a porous medium initially filled by a gas and
water are considered. Self-similar solutions of an axisymmetric problem, which describe the distributions of the basic parameters
in the reservoir, are constructed. The existence of solutions is demonstrated, which predict gas hydrate formation both on
the frontal surface and in the volume zone.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 137–150, May–June, 2008. 相似文献
20.
N. A. Rubtsov S. D. Sleptsov N. A. Savvinova 《Journal of Applied Mechanics and Technical Physics》2006,47(3):377-383
Numerical modeling of the single-phase Stefan problem in a semitransparent layer with transparent, nonabsorbing, and partially
radiation-absorbing boundaries is performed. It is shown that at low temperatures of the medium, convection is a determining
factor on the boundary of the irradiated sample, and at high temperatures, radiation is predominant. The absence of absorption
on the boundaries of the layer leads to acceleration of the heating of the plate and considerable deceleration of melting
processes.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 84–91, May–June, 2006. 相似文献