Issue 1/2008

UDK 532.517.4+519.63
AN OVERVIEW OF ADVANCED NUMERICAL CAPABILITIES FOR TURBULENT MIXING ANALYSES / A. N. Razin, Yu. A. Trutnev // P. 3

A summary is presented of advanced numerical techniques designed for turbulent mixing simulations and are used both to describe model experiments and to solve specific practical problems. The key issues are stated that must be taken into consideration in substantiations of numerical data on turbulent flows that develop from Richtmeyer – Meshkov instability, and also in development of new physical models and numerical codes.

UDK 532.517.4+519.63
NUMERICAL RESULTS ON TURBULENT MIXING IN 1D FLOWS OBTAINED USING ADVANCED COMPUTATION CAPABILITIES / A. N. Razin, Yu. A. Trutnev, E. V. Shaporenko // P. 14

Numerical results are discussed obtained for 1D flows with turbulent mixing. The flows addressed are limited to cases in which turbulence in gaseous systems develops due to shock wave impact. Setups are described of known experiments that have provided the most informative experimental data. Numerical simulation results are presented for the selected experiments.

UDK 539.1.01; 514.83
A CONFORMALLY INVARIANT APPROACH TO ESTIMATION OF RELATIONS BETWEEN PHYSICAL QUANTITIES / M. V. Gorbatenko, G. G. Kochemasov // P. 24

A. V. Pushkin's approach based on conformal geometrodynamics (CGD) to calculation of quantitative relations between physical quantities is presented and analyzed. In the simplest cases of the stationary solutions to the CGD equations the approach implies separation of internal and external parts (relative to a certain boundary) from the solutions and using inverse transformations transforming the parts into each other. For the quasi-stationary (metastable) states, the possibility of the nonperturbative calculation of their lifetimes is shown. The approach is illustrated by several examples. In particular, it is shown that the Dirac "large number hypothesis" is a consequence of the approach. Also, the evaluated radiation lifetime of the first excited level of 2p hydrogen atom and neutron lifetime are presented.

UDK 539.1.01; 514.83
CONFORMAL GEOMETRODYNAMICS: EXACT NONSTATIONARY SPHERICALLY SYMMETRIC SOLUTIONS / M. V. Gorbatenko // P. 34

A nonstationary spherically symmetric problem for conformal geometrodynamics equations is considered and general exact solutions in quadratures are obtained. Involvement of Weyl degrees of freedom allows us to consider the problem with arbitrary initial data, as for the conformal geometrodynamics equations the Cauchy problem is set up without connections to initial data. Two exact nonstationary special solutions are written out in the explicit form. The results of this paper are not confined with the framework of the perturbation theory and open up new avenues for study of the process of space-time singularity evolution in time.

UDK 537.534.7
STOPPING OF IONS IN ELEMENTAL MATTER. IV. COMPARISON OF VARIOUS EFFECTS IN THE INTERMEDIATE VELOCITY REGION / D. K. Kovshov // P. 43

Four corrections to the Bethe formula at 10²–10⁴ keV/amu are investigated on the basis of semiempirical stopping formula. For light ions shell corrections prevail, except the case of lightest matters. For heavy ions effective charge is essential, contrary to Sigmund and Schinner. Barkas correction does not exceed the uncertainty of semiempirical formula.

UDK 537.534.7
STOPPING OF IONS IN ELEMENTAL MATTER. V. STOPPING POWER OSCILLATIONS / D. K. Kovshov // P. 50

Z_o- and Z-oscillations of stopping power are investigated on the basis of semiempirical stopping formula. Qualitative theory is proposed for Z_o-oscillations; they are explained in terms of shell structure of target material and relations between orbital velocities of electrons in different subshells. Z-oscillations are found to be partly consistent with Briggs-Pathak theory.

UDK 539.17
THE THEORY OF SIMILARITY IN THE FRAMEWORK OF ONE-VELOCITY NEUTRON KINETICS OF QUASI-STATIONARY SYS-TEMS / N. B. Babichev, I. V. Lutikov, V. P. Neznamov // P. 56

Quasi-stationary systems with finite dimensions and arbitrary geometry that are similar in terms of neutron kinetics have been studied. The goal of this study is to find similar systems by analyzing neutrons kinetic equation. Similarity formulae have been derived for several classes of quasi-stationary systems.

UDK 539.12.17
EFFECTIVE DIFFUSIVITY AS APPLIED TO THE DESCRIPTION OF HYDROGEN PERMEATION THOUGH A MATTER WITH TRAPS UNDER DIFFERENT TRANSPORT CONDITIONS / A. A. Pisarev, I. V. Tsvetkov, S. S. Yarko // P. 65

The paper discusses the possibility of using effective diffusivity for the description of hydrogen transport through walls with defects. The walls are considered, permeation through which in the absence of defects is limited either by diffusion or by the surface, or when intermediate transport conditions occur. Particular aspects of experimental data interpreting are analyzed.