V. Yu. Levashov

Condensation from a vapor-gas mixture on a plane surface

An approach is developed, which was previously suggested for the investigation of intensive condensation of pure vapor in application to a one-dimensional steady-state problem of condensation in the presence of a noncondensable component. Results are obtained, which make possible the estimation of the parameters of the limiting modes of condensation from a vapor-gas binary mixture.

Vapor Flow with Evaporation–Condensation on Solid Particles

Strongly nonequilibrium vapor (gas) flows in a region filled by solid particles are considered with allowance for particle‐size variation due to evaporation–condensation on the particle surface. The study is performed by directly solving the kinetic Boltzmann equation with allowance for the transformation of the distribution function of gas molecules due to their interaction with dust particles.

Selective water vapor cryopumping through argon

A selective cryopumping process for water vapor control takes place in vacuum systems for web coating or plasma operations, such as sputter deposition, etching, etc. Excessive water vapor content will affect the quality of the processes and final products. These vacuum systems typically operate at pressures corresponding to transitional or viscous flow regimes, and water vapor cryopumping is highly limited by diffusion of water vapor molecules through a noncondensable process gas (argon, air). An analytical model was created to describe water vapor condensing process through a noncondensable gas diffusion barrier. The model accounts for the collisions of different molecules by means of Boltzmann kinetic equations for two-component rarefied gas. It was assumed that water vapor content is about three orders of magnitude lower than that of the noncondensable gas (argon). Cryopumping process was analyzed for two simplified cases when water vapor source and cryosurface are parallel plates and coaxial cylinders...

Numerical simulation of water droplet evaporation into vapor–gas medium

Numerical simulation has been employed to consider water droplet evaporation into a vapor–gas medium. An approximate approach has been proposed that makes it possible to take into account the effect of a noncondensable component on the character of variations in the droplet temperature during evaporation. The results of the calculations have been compared with the published experimental data.

Investigation of Flows of a Gas–Dust Mixture by the Methods of Molecular-Kinetic Theory

Using a direct numerical solution of the Boltzmann kinetic equation the problem of the flow of a gas–dust mixture is investigated with allowance for the motion of the dust. The qualitative analysis made has shown that in describing the flow of gas–dust mixtures it becomes possible to simplify the system of kinetic equations. The dependences of the density, the temperature, and the velocity of the gas on the coordinate have been obtained for different concentrations and velocities of the dust particles.

Analysis of the flow of rarefied gas through a layer of a porous body on the basis of direct numerical solution of the kinetic Boltzmann equation

The problem of the flow of rarefied gas through a layer of a porous body, which is replaced by a homogeneous system of immobile spherical particles, is solved on the basis of the method of direct numerical solution of the kinetic Boltzmann equation. The effect of the spherical particles on the gas molecules is described as a kind of “boundary condition” distributed in space. Dependences of the density, temperature, and velocity on the coordinate in physical space are obtained; cross sections of the distribution function of the gas molecules by velocities are presented.

Investigation the evaporation-condensation problem by means of the joint numerical solution of the Boltzmann kinetic equation and interface modelling

The paper is devoted to research of the heat and mass transfer processes in liquid and vapor phase on the basis of the uniform approach assuming the through description of liquid, interface and vapor. Multiparticles interactions in liquid will be taken into account. The problem is studied when temperature in the depth of liquid differs from temperature in the vapor region. In this case there are both mass flux and heat flux. The study of influence of the correlations resulting from interactions of molecules set in thin near-surface liquid layers and an interface on intensity of evaporation is made. As a result of calculations the equilibrium line of the liquid-vapor saturation is obtained, which corresponds good enough with experimental data. Distributions of density, temperature, pressure, heat and mass fluxes, both in a liquid and in vapor are also presented.