共查询到20条相似文献,搜索用时 33 毫秒
1.
A two-scale model of ion transfer in a porous medium is obtained for one-dimensional horizontal flows under the action of
a pressure gradient and an external electric field by the method of homogenization. Steady equations of electroosmotic flows
in flat horizontal nano-sized slits separated by thin dielectric partitions are averaged over a small-scale variable. The
resultant macroequations include Poisson’s equation for the vertical component of the electric field and Onsager’s relations
between flows and forces. The total horizontal flow rate of the fluid is found to depend linearly on the pressure gradient
and external electric field, and the coefficients in this linear relation are calculated with the use of microequations.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 162–173, July–August, 2008. 相似文献
2.
Yu. G. Gubarev 《Fluid Dynamics》1999,34(1):126-132
The problem of the linear stability of a single particular class of helical steady-state flows of an ideal incompressible
infinitely-conducting fluid in a magnetic field is studied. A necessary and sufficient condition of stability of this class
of flows with respect to perturbations of the same symmetry type is obtained by the direct Lyapunov method [1, 2]. A priori
two-sided exponential estimates of the perturbation growth are derived, the corresponding exponents being calculated using
the steady flow parameters and the initial data for the perturbations. A class of the most rapidly growing perturbations is
identified and an exact formula for determining their growth rate is obtained. An example of steady-state flows and initial
perturbations whose linear stage of development with time can be described by means of the estimates obtained is constructed.
Novosibirsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 150–156, January–February,
1999.
The work was carried out with financial support from the Russian Foundation for Basic Research (project No. 96-01-01771). 相似文献
3.
V. Yu. Liapidevskii 《Journal of Applied Mechanics and Technical Physics》2000,41(4):647-657
A mathematical model for the evolution of a mixing layer in shear flows is constructed. The problem of a mixing layer with
pressure gradient is solved: in particular, the distributions of the velocity and basic characteristics of turbulent flow
in the mixing layer are obtained.
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 4, pp. 81–92, July–August, 2000. 相似文献
4.
S. N. Aristov 《Fluid Dynamics》1998,33(6):929-932
New exact solutions of the Navier-Stokes equations are obtained for steady-state three-dimensional conical flows. In this
class of flows the velocity decreases in inverse proportion to the distance from the source and the input equations reduce
to two-dimensional ones. It is shown that in the spherical coordinate system the equations of motion reduce to a single nonlinear
equation with respect to a scalar function which depends on the polar angles. The case in which this equation reduces to the
integrable Liouville equation is discussed. This makes it possible to obtain a wide class of three-dimensional solutions in
analytic form.
Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 144–148, November–December,
1998.
The work was carried out with financial support from the Russian Foundation for Basic Research (project No. 97-01-00063). 相似文献
5.
A macroscopic law of flow of a viscoplastic Schwedoff-Bingham fluid through a porous medium is obtained on the basis of percolation
theory with allowance for viscous and inertial losses. The asymptotics of the flow law are estimated and expressions for determining
the limiting pressure gradient as a function of the microinhomogeneity parameters are given. Satisfactory qualitative agreement
between the theoretical and known experimental data is observed.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 68–73, January–February,
1999. 相似文献
6.
N. I. Makarenko 《Journal of Applied Mechanics and Technical Physics》1999,40(2):249-257
The problem of steady-state flows in a layer of a continuously stratified fluid is considered. The sufficient condition of
existence of families of shear flows that are consistent with the meaning of the laws of conservation of mass, momentum, and
energy with a uniform flow is given. Approximate solutions of the smooth-bore type, which describe the wave transitions for
pairs of conjugate flows of the first spectral mode, are obtained.
Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 2, pp. 69–78. March–April, 1999. 相似文献
7.
V. K. Andreev 《Journal of Applied Mechanics and Technical Physics》2008,49(4):598-609
A study is made of an invariant solution of the equations of a viscous heat-conducting fluid, which is treated as unidirectional
motion of two such fluids in a plane layer with a common boundary under the action of an unsteady pressure gradient. A priori
estimates of the velocity and temperature are obtained. The steady state is determined, and it is shown (under some conditions
on the pressure gradient) that, at larger times, this state is the limiting one. For semiinfinite layers, a solution in closed
form is obtained using the Laplace transform.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 94–107, July–August, 2008. 相似文献
8.
The linear stability of flow in a horizontal fluid layer is investigated within the framework of thermoacoustic convection.
The flow is initiated by a longitudinal temperature gradient and the propagation of an acoustic wave in the fluid. Instability
modes corresponding to perturbations of both plane and longitudinal roller and oblique wave type are detected. Using weakly
nonlinear analysis, it is shown that these regimes develop softly; the stability of various secondary flows is investigated
for small supercriticalities.
Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 10–21, May–June, 2000.
The work was carried out with partial support from the Program of State Support for Leading Science Schools (grant No. 96-015-96084). 相似文献
9.
Homogeneous heavy fluid flows over an uneven bottom are studied in a long-wave approximation. A mathematical model is proposed
that takes into account both the dispersion effects and the formation of a turbulent upper layer due to the breaking of surface
gravity waves. The asymptotic behavior of nonlinear perturbations at the wave front is studied, and the conditions of transition
from smooth flows to breaking waves are obtained for steady-state supercritical flow over a local obstacle.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 3–11, May–June, 2006. 相似文献
10.
A. V. Kazakov 《Fluid Dynamics》1998,33(6):850-855
The results of a numerical investigation of the effect of thermal energy supply on a swirling viscous heat-conducting gas
flow in a subsonic cocurrent stream are presented. The initial stage of development of the swirling flow in the neighborhood
of the vortex axis with constant circulation in the outer flow region is considered for two different distributions of the
streamwise velocity vector component which simulate a swirling jet-type flow and a wake flow with a streamwise velocity deficit.
The effect of local volume energy supply in the neighborhood of the vortex axis, the circulation of the azimuthal velocity
component, and the longitudinal pressure gradient in the inviscid stream on the development of the swirling flow and the process
of breakdown of cocurrent vortex flows is investigated.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 47–53, November–December,
1998.
The work was carried out with financial support from the Russian Foundation for Basic Research (project No. 96-01-00586). 相似文献
11.
Electrogas- and electrohydrodynamic control of gas and liquid jets and flows. 2. Physical principles
V. S. Nagornyi 《Journal of Applied Mechanics and Technical Physics》2000,41(3):408-415
The paper deals with the electrophysical principles of the method of electrogas- and electrohydrodynamic conversion of electric
signals to pneumatic (hydraulic) signals and vice versa for the control of gas and liquid jets and flows in electropneumohydraulic
systems, including problems of formulating requirements for the working media and electric circuits of converters, estimating
the limiting ranges of pressure, velocity, and temperatures of the working media and limiting dynamic possibilities, and determining
conditions for production of potential signals, stable control, and extension of the control ranges.
St. Petersburg State Technical University, St. Petersburg 195251. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika,
Vol. 41, No. 3, pp. 34–42, May–June, 2000. 相似文献
12.
The effect of flow intensification in small-sized vortex cells on the flow pattern in the near wake downstream of a cylinder
and the cylinder drag in laminar and turbulent flows is analyzed on the basis of a numerical simulation of the two-dimensional
steady-state flow past a circular cylinder with rotating cylindrical bodies built into the cylinder contour.
St. Petersburg, Saratov. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 88–96,
July–August, 2000.
The study was carried out with the support of the Russian Foundation for Basic Research (projects Nos. 99-01-01115 and 99-01-00772). 相似文献
13.
Measurements of mean velocity and turbulent quantities have been carried out when the wake of a symmetrical airfoil interacts
with the boundary layer on the (i) walls of a straight duct/diffuser and (ii) convex and concave walls of a curved duct/diffuser.
The effects of adverse pressure gradient and of curvatures on the interaction are studied separately and in combination. Six
cases are considered, viz. with (i) neither pressure gradient nor curvature, (ii) adverse pressure gradient and no curvature,
(iii) and (iv) convex curvature with zero and adverse pressure gradients, respectively, (v) and (vi) concave curvature with
zero and adverse pressure gradients, respectively. For the flows with curvature, the curvature parameter δ/R is 0.023, and for the flows with adverse pressure gradient, the Clauser pressure gradient parameter β is 0.62. The individual influences of adverse pressure gradient and convex and concave curvatures on the boundary layer are
similar to those observed by earlier investigations. It is further observed that the combined effect of concave/convex curvature
and the adverse pressure gradient causes higher turbulence intensities than the sum of the individual effects. The effect
of curvature is to make the wake asymmetric, and in combination with adverse pressure gradient the asymmetry increases. It
is observed that the adverse pressure gradient causes faster wake–boundary-layer interaction. Comparing measurements in a
straight duct, a curved duct, a curved diffuser and a straight diffuser, it is seen that the convex curvature reduces the
boundary layer thickness. The asymmetry in wake development compensates for this effect and the wake–boundary-layer interaction
on a convex surface is almost the same as that on a straight surface. In the case of interaction with the boundary layer on
a concave surface, the curvature increases the boundary layer thickness and causes enhanced turbulence intensities. However,
the asymmetry in wake is such that the extent of wake is lower towards the boundary layer side. As a result, the wake–boundary-layer
interaction on concave surface is almost the same as on a straight surface. The interaction is faster in the presence of adverse
pressure gradient.
Received: 16 June 2000 / Accepted: 17 May 2001 相似文献
14.
In this paper the following problem is solved in the linear approximation. Let a flat plate separate two uniform inviscid
fluid flows with different steady-state densities and velocities. These flows are subject to small time-dependent disturbances
due to plate deformation. This problem is solved for arbitrary deformations as well as in the case of the angular harmonic
oscillations of a flapping mover. The time-dependent forces acting on the plate are determined, together with the dynamic
characteristics of the mover and the position of the fluid-fluid interface.
Kazan'. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 55–64, January–February,
1994. 相似文献
15.
This study reports an investigation on the characteristics of single-phase (brine) and two-phase (DNAPL–brine) flows in induced
fractures. The fracture aperture and fluid phase distributions were determined using X-ray computer tomography. In the single-phase
flow tests, the pressure gradient across the induced fractures increases linearly with increasing flow rate. However, models
based on the measured aperture do not yield a consistent match with the experimental data because the effect of pressure losses
due to aperture variation and undulation are not taken into account. In the two-phase flow tests, the measured phase distributions
reveal that the flow pattern is dominated by a dispersed or mixed flow in which either DNAPL or brine phase is discontinuous.
The channel flow pattern, in which DNAPL and brine phases are continuous in the fracture and well represented by the widely
used Romm’s relative permeability relationship was not observed in this study. In contrast, a Lockhart–Martinelli-type correlation
developed for gas–liquid flow in pipes was found to match the pressure gradient and phase saturation results obtained from
the laboratory tests. 相似文献
16.
M. S. Kotel’nikova B. A. Lugovtsov 《Journal of Applied Mechanics and Technical Physics》2009,50(2):243-250
This paper considers the problem of the evolution of azimuthal perturbations in axisymmetric magnetohydrodynamic. flows of
an ideally conducting inviscid fluid with circular streamlines. The fluid is. in a toroidal gap between two surfaces with
constant values of the stream function. The equations of. fluid motion are derived in the approximation of infinitely a narrow
gap. The parameters at which. spontaneous swirling is possible are determined numerically, and the properties of secondary
swirling. flows resulting from instability of the initial steady-state poloidal flow are established.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 89–97, March–April, 2009. 相似文献
17.
G. Ya. Dynnikova 《Fluid Dynamics》2000,35(1):24-32
An expression with a constant value over all space (including multiply connected domains) relating the pressure function to
the square of the velocity and the characteristics of the traveling vortices is derived for a time-dependent ideal incompressible
fluid flow with nonzero vorticity. When there are bodies in the flow, they must also be represented in the form of traveling
vortices. For steady-state flow the formula obtained goes over into the Bernoulli integral and for time-dependent irrotational
flow into the Cauchy-Lagrange integral.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 31–41, January–February,
2000.
The work was carried out with financial support from the Russian Foundation for Basic Research (project No. 98-01-00156 and
project No. 96-15-9603 for the support of leading science schools). 相似文献
18.
This paper deals with some unsteady unidirectional transient flows of generalized Burgers’ fluid in an annular pipe. Exact
solutions of some unsteady flows of generalized Burgers’ fluid in an annular pipe are obtained by using Hankel transform and
Laplace transform. The following two problems have been studied: (1) Poiseuille flow due to a constant pressure gradient;
(2) axial Couette flow in a annulus. The well known solutions for Navier-Stokes fluid, as well as those corresponding to a
Maxwell fluid, a second grade fluid and an Oldroyd-B fluid appear as limiting cases of our solutions. 相似文献
19.
A steady-state plane channel flow of viscous incompressible fluid with no-slip and heat transfer boundary conditions is considered.
The flow is induced by a fixed pressure difference and the fluid viscosity depends on the temperature in accordance with a
power law. It is shown numerically that the dependence of the Peclet number on the nondimensional pressure difference is not
single-valued. An investigation of the solution’s dependence on the Biot number shows that for Biot numbers greater than unity
the velocity profile has a point of inflection.
Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 75–80, March–April, 2000.
The work received financial support from the Russian Foundation for Basic Research (project N97-01-00063). 相似文献
20.
The interaction between a normally impinging shock wave and the boundary layer on a plate with slip is studied in the neighborhood
of the leading edge using various experimental methods, including special laser technology, to visualize the supersonic conical
gas flows. It is found that in the “non-free” interaction, when the leading edge impedes the propagation of the boundary layer
separation line upstream, the structure of the disturbed flow is largely identical to that in the developed “free” interaction,
but with higher parameter values and gradients in the leading part of the separation zone. The fundamental property of developed
separation flows, namely, coincidence of the values of the pressure “plateau” in the separation zone and the pressure behind
the oblique shock above the separation zone of the turbulent boundary layer, is conserved.
Moscow. e-mail: ostap@inmech.msu.su. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3,
pp. 57–69, May–June, 2000.
The work was carried out with financial support from the Russian Foundation for Basic Research (project No. 97-01-00099). 相似文献