1,041 research outputs found
The equation of state of a partly homogenized plasma of low-dense porous matter
The equation of state (EOS) of a low-density porous substance plasma is
proposed in the form of continuous media EOS containing, as a pressure control
parameter, the degree of plasma homogenization, which is function of the
initial porous structure, as well as of the current values of plasma density
and temperature. Using the partially-homogenized-plasma EOS an approximate
analytical solution is found and numerical calculations were performed of the
problem of thermal expansion of a flat layer of porous matter. The features of
the obtained results are discussed in comparison with the case of a continuous
substance of equivalent chemical composition. The proposed equation of state is
used to analyze the experimental data on porous substance heating with laser
and X-ray pulses.Comment: 20 pages, 4 figure
Verification and Improvement of Flamelet Approach for Non-Premixed Flames
Studies in the mathematical modeling of the high-speed turbulent combustion has received renewal attention in the recent years. The review of fundamentals, approaches and extensive bibliography was presented by Bray, Libbi and Williams. In order to obtain accurate predictions for turbulent combustible flows, the effects of turbulent fluctuations on the chemical source terms should be taken into account. The averaging of chemical source terms requires to utilize probability density function (PDF) model. There are two main approaches which are dominant in high-speed combustion modeling now. In the first approach, PDF form is assumed based on intuitia of modelliers (see, for example, Spiegler et.al.; Girimaji; Baurle et.al.). The second way is much more elaborate and it is based on the solution of evolution equation for PDF. This approach was proposed by S.Pope for incompressible flames. Recently, it was modified for modeling of compressible flames in studies of Farschi; Hsu; Hsu, Raji, Norris; Eifer, Kollman. But its realization in CFD is extremely expensive in computations due to large multidimensionality of PDF evolution equation (Baurle, Hsu, Hassan)
Flamelet Model Application for Non-Premixed Turbulent Combustion
The current Final Report contains results of the study which was performed in Scientific Research Center 'ECOLEN' (Moscow, Russia). The study concerns the development and verification of non-expensive approach for modeling of supersonic turbulent diffusion flames based on flamelet consideration of the chemistry/turbulence interaction (FL approach). Research work included: development of the approach and CFD tests of the flamelet model for supersonic jet flames; development of the simplified procedure for solution of the flamelet equations based on partial equilibrium chemistry assumption; study of the flame ignition/extinction predictions provided by flamelet model. The performed investigation demonstrated that FL approach allowed to describe satisfactory main features of supersonic H 2/air jet flames. Model demonstrated also high capabilities for reduction of the computational expenses in CFD modeling of the supersonic flames taking into account detailed oxidation chemistry. However, some disadvantages and restrictions of the existing version of approach were found in this study. They were: (1) inaccuracy in predictions of the passive scalar statistics by our turbulence model for one of the considered test cases; and (2) applicability of the available version of the flamelet model to flames without large ignition delay distance only. Based on the results of the performed investigation, we formulated and submitted to the National Aeronautics and Space Administration our Project Proposal for the next step research directed toward further improvement of the FL approach
Comparison of Geant4 hadron generation with data from the interactions with beryllium nuclei of +8.9 GeV/c protons and pions, and of -8 GeV/c pions
Hadron generation in the Geant4 simulation tool kit is compared with
inclusive spectra of secondary protons and pions from the interactions with
beryllium nuclei of +8.9 GeV/c protons and pions, and of -8.0 GeV/c pions. The
data were taken in 2002 at the CERN Proton Synchrotron with the HARP
spectrometer. We report on significant disagreements between data and simulated
data especially in the polar-angle distributions of secondary protons and
pions.Comment: 15 pages, 13 figure
Pion Polarizability in the NJL model and Possibilities of its Experimental Studies in Coulomb Nuclear Scattering
The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model,
where the quark loops (in the mean field approximation) and the meson loops (in
the approximation) are taken into account. We show that quark loop
contribution dominates, because the meson loops strongly conceal each other.
The sigma-pole contribution plays the main role and
contains strong t-dependence of the effective pion polarizability at the region
. Possibilities of experimental test of this sigma-pole
effect in the reaction of Coulomb Nuclear Scattering are estimated for the
COMPASS experiment.Comment: 11 pages, 8 figure
Cross-Sections of Large-Angle Hadron Production in Proton- and Pion-Nucleus Interactions V: Lead Nuclei and Beam Momenta from +/-3 Gev/c to +/-15 Gev/c
We report on double-differential inclusive cross-sections of the production
of secondary protons, charged pions, and deuterons, in the interactions with a
5% nuclear interaction length thick stationary lead target, of proton and pion
beams with momentum from +/-3 GeV/c to +/-15 GeV/c. Results are given for
secondary particles with production angles 20 to 125 degrees. Cross-sections on
lead nuclei are compared with cross-sections on beryllium, copper, and tantalum
nuclei.Comment: 67 pages, 13 figures, 47 table
Cross-Sections of Large-Angle Hadron Production in Proton- and Pion-Nucleus Interactions III: Tantalum Nuclei and Beam Momenta from +/-3 Gev/c to +/-15 Gev/c
We report on double-differential inclusive cross-sections of the production
of secondary protons, charged pions, and deuterons, in the interactions with a
5% nuclear interaction length thick stationary tantalum target, of proton and
pion beams with momentum from +/-3 GeV/c to +/-15 GeV/c. Results are given for
secondary particles with production angles between 20 and 125 degrees. They are
of particular relevance for the optimization of the design parameters of the
proton driver of a neutrino factory.Comment: 68 pages, 12 figures, corrections in v2: added 'HARP -CDP group' to
author name, corrected two typos in Table 4 (last two p values for 65-90
degrees were all 0.972
Cross-sections of large-angle hadron production in proton-- and pion--nucleus interactions VIII: aluminium nuclei and beam momenta from {\pm}3 GeV/c to {\pm}15 GeV/c
We report on double-differential inclusive cross-sections of the production
of secondary protons, charged pions, and deuterons, in the interactions with a
5% {\lambda}int thick stationary aluminium target, of proton and pion beams
with momentum from \pm3 GeV/c to \pm15 GeV/c. Results are given for secondary
particles with production angles between 20 and 125 degrees. Cross-sections on
aluminium nuclei are compared with cross-sections on beryllium, carbon, copper,
tin, tantalum and lead nuclei.Comment: 71 pages, 16 figures, 47 table
Cross-sections of large-angle hadron production in proton- and pion-nucleus interactions VI: carbon nuclei and beam momenta from \pm 3 GeV/c to \pm 15 GeV/c
We report on double-differential inclusive cross-sections of the production
of secondary protons, charged pions, and deuterons, in the interactions with a
5% nuclear interaction length thick stationary carbon target, of proton and
pion beams with momentum from \pm 3 GeV/c to \pm 15 GeV/c. Results are given
for secondary particles with production angles between 20 and 125 degrees.
Cross-sections on carbon nuclei are compared with cross-sections on beryllium,
copper, tantalum and lead nuclei.Comment: 67 pages, 13 figure
On the flaws in 'Official' HARP's data analysis
We present a complete account of the flaws in the data analysis of 'Official' HAR
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