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Asymptotic solutions are constructed for
the problem of the shock-wave structure
in mixtures of gases with disparate
molecular masses. The effect of
emergence of a plateau on the density
profile of the light component and
nonmonotonicity of the temperature
profile of the heavy component is
described. Based on a comparison with
calculations of the full model, the
range of applicability of asymptotic
solutions is determined.

The structure of a supersonic
underexpanded low-pressure-ratio jet
exhausted from a nozzle with variable
geometry of the entrance section is
experimentally studied. Total pressure
distributions in the initial cross
sections of the examined jets are
obtained. Based on these distributions,
the coordinates of the mixing-region
boundaries are found. The curvature of
streamlines in the mixing layer within
the first two barrels of an
underexpanded jet is determined. A
dependence generalizing the measurement
results on the curvature of streamlines
in the first barrel of a weakly
underexpanded jet is obtained in
dimensionless coordinates.

Using the method of moments in the space
of wavenumbers, a class of models of a
developed turbulent flow of an
incompressible fluid in a flat-plate
boundary layer is proposed. The models
are based on an analysis of the Navier

The effect of translational nonequilibrium
on the course of chemical reactions in a
shock wave is studied using the "beam

An analytical and numerical study of
protective properties of hot-air screens
is performed for a plane wave with a
triangular profile. The reduction of the
shock-wave pressure behind the screen is
only observed at temperatures higher a
certain critical value; at lower
temperatures, the pressure is higher
than that in a shock wave traveling in
an isothermal gas. With allowance for
real properties of air, an analytical
relation between the critical
temperature of the hot screen and the
incident-wave intensity is obtained.

The problem of a rarefied gas flow in a
channel for arbitrary Knudsen numbers
has been solved analytically for the
first time in the case where the
scattering of gas molecules on the
channel walls can be described by
specular-diffuse boundary conditions.
The mean free path of gas molecules is
assumed to be constant, i.e., the
collision frequency is proportional to
molecular velocity. The gas moves under
the action of a streamwise temperature
gradient. Exact relations for heat and
mass fluxes and for mean-mass velocity
are obtained. It is shown that the
Onsager relations are valid within the
entire range of Knudsen numbers in the
problem of heat and mass transfer in a
channel. The dependence of heat and mass
fluxes on the Knudsen number (channel
thickness) is analyzed. A comparison
with available results is performed.

The paper deals with construction and
investigation of a mathematical model
for ground water flow from the earth's
surface over a vertical impermeable
screen with flow interception by a drain
located on the screen surface.

Subgrid modeling of a filtration flow of
a fluid in an inhomogeneous porous
medium is considered. An expression for
the effective permeability coefficient
for the large-scale component of the
flow is derived using the scale-
invariance hypothesis. The model
obtained is verified by numerical
simulation of the complete problem.

The previously obtained criterion which
distinguishes water injection regimes
accompanied by vaporization of injected
water or vapor condensation is extended
to the radially symmetric problem. The
effects of cold liquid injection rate
and the initial temperature, pressure,
and capacity of a geothermal reservoir
on hydrodynamic and temperature profiles
are examined.

This paper considers a modification of
the "predictor" stage of Godunov's
discontinuity decay method for problems
of nonlinear deformation of soft soils.
Soil behavior is described by the
Grigoryan's taking into account
nonlinear diagrams of volumetric
deformation, shear strength, and
plasticity. Assumptions are formulated
that reduce the auxiliary problem of the
decay of a discontinuity in soils to the
well-known problem that has a unique
solution. Examples of numerical
calculations are given.