scholarly journals Fractional diffusant model of a multicomponent inhomogeneous gas mixture as a basis for the diffusant approximation

2021 ◽  
Vol 2100 (1) ◽  
pp. 012023
Author(s):  
B M Burakhanov
Keyword(s):  
Multicomponent Mixture ◽  
Velocity Fields ◽  
Mixture Component ◽  
Gas Mixture ◽  
Correct Description ◽  
Fractional Model ◽  
Velocity Motion ◽  
Inhomogeneous Gas

Abstract It can be shown that for a correct description of the motion of an inhomogeneous multicomponent mixture of gases, such concepts as a multi-velocity continuum and interpenetrating motion are not enough. This is the basis for the introduction of the concept of “poly-velocity motion”. The reason for the need to use this concept is that to describe the motion of each component of an inhomogeneous mixture, it is necessary to use not one, but two velocity fields. The use of two velocity fields to describe the motion of a mixture component is the basis for constructing a fractional model of the mixture component, in which each component is divided into two fractions. This model serves as the basis for constructing the proposed fractional diffusant model of a multicomponent inhomogeneous gas mixture.

Kinetic and thermodynamic treatments of a neutral binary gas mixture affected by a nonlinear thermal radiation field

2012 ◽  
Vol 90 (2) ◽  
pp. 137-149 ◽  
Author(s):  
Aly Maher Abourabia ◽  
Taha Zakaraia Abdel Wahid
Keyword(s):  
Thermal Radiation ◽  
Radiation Field ◽  
Molar Fraction ◽  
Distribution Functions ◽  
Mixture Component ◽  
Gas Mixture ◽  
Nonlinear Thermal Radiation ◽  
Binary Gas Mixture ◽  
Kinetic Coefficients ◽  
Thermal Radiation Field

In the present study, the kinetic and the irreversible thermodynamic properties of a binary gas mixture, under the influence of a thermal radiation field, are presented from the molecular viewpoint. In a frame comoving with the fluid, the Bhatnagar–Gross–Krook model of the kinetic equation is analytically applied, using the Liu–Lees model. We apply the moment method to follow the behavior of the macroscopic properties of the binary gas mixture, such as the temperature and the concentration. The distinction and comparisons between the perturbed and equilibrium distribution functions are illustrated for each gas mixture component. From the viewpoint of the linear theory of irreversible thermodynamics we obtain the entropy, entropy flux, entropy production, thermodynamic forces, and kinetic coefficients. We verify the second law of thermodynamics and celebrated Onsager’s reciprocity relation for the system. The ratios between the different contributions of the internal energy changes, based upon the total derivatives of the extensive parameters, are estimated via Gibbs’ formula. The results are applied to the argon–neon binary gas mixture, for various values of both the molar fraction parameters and radiation field intensity. Graphics illustrating the calculated variables are drawn to predict their behavior and the results are discussed.

scholarly journals Числове та експериментальне дослідження наповнення резервуару компонентом газової суміші

2021 ◽  
pp. 63-72
Author(s):  
Ольга Володимирівна Шипуль ◽  
Сергій Олександрович Заклінський ◽  
Володимир Вікторович Комбаров ◽  
Олексій Анатолійович Павленко ◽  
Вадим Олегович Гарін
Keyword(s):  
Mathematical Models ◽  
Numerical Models ◽  
Control Point ◽  
Calculated Data ◽  
Full Scale ◽  
Mixture Component ◽  
Gas Mixture ◽  
Gas Temperature ◽  
Gas Dynamic ◽  
Simulation Results

The subject of the research is mathematical models of a gas-dynamic non-stationary process of filling a vessel with a component of a gas mixture. The aim of the study is the scientific and experimental substantiation of the choice of a model of filling a vessel with a component of a gas mixture with a given accuracy. The objectives of the study are to conduct full-scale experiments on filling the vessel with gas for further verification of the gas mixture generation control system, as well as in the development of adequate mathematical models of gas-dynamic flow, the analysis of simulation results, and the use of verified results in the system of automated generation of a gas mixture of a given accuracy by assessing the mass of its components depending on the filling parameters. The tasks are solved by studying the results of numerical modeling of the process and full-scale experiments. The following results are obtained. A series of full-scale experiments on filling a vessel with high-frequency monitoring of the pressure and temperature of the gas being filled was carried out. Significant factors were analyzed. The use of SAS SST turbulence models was substantiated. Models of the gas-dynamic unsteady process of filling the vessel with a component of the gas mixture for various values of the mass flow rate had been built. All the simulations were carried out using the ANSYS CFX software package. The influence of considering a heat exchange with the vessel walls on the studied parameters of the mixture is determined, namely: pressure, gas temperature averaged over the volume, gas temperature in a control point, mass of the component of a gas mixture. It was found that the deviation of the calculated data when using a model with an adiabatic condition on the wall compared to a model with a constant temperature regime is: for pressure – no more than 5 %, for averaged temperature – 6 %, for the temperature at the monitor point – 9 %, for mass – 1.5 %. The discrepancy between the simulation results and the full-scale experiment does not exceed 12 % in pressure and temperature at the monitor point, as well as 4 % in the mass of the component. By the experimentally determined accuracy parameter of the gas mixture (the mass of the mixture component in particular), the numerical models had been corrected to provide the mass value error of no more than 0.5 %.

C. The Continuous Spectrum of Pulsating Variable Stars

1967 ◽  
Vol 28 ◽  
pp. 177-206
Author(s):  
J. B. Oke ◽  
C. A. Whitney
Keyword(s):  
Continuous Spectrum ◽  
Variable Stars ◽  
Velocity Fields ◽  
The Other ◽  
Line Spectrum ◽  
Direct Information ◽  
Thermodynamic Structure ◽  
Diagnostic Interpretation ◽  
Pulsating Variable Stars ◽  
The Continuum

Pecker:The topic to be considered today is the continuous spectrum of certain stars, whose variability we attribute to a pulsation of some part of their structure. Obviously, this continuous spectrum provides a test of the pulsation theory to the extent that the continuum is completely and accurately observed and that we can analyse it to infer the structure of the star producing it. The continuum is one of the two possible spectral observations; the other is the line spectrum. It is obvious that from studies of the continuum alone, we obtain no direct information on the velocity fields in the star. We obtain information only on the thermodynamic structure of the photospheric layers of these stars–the photospheric layers being defined as those from which the observed continuum directly arises. So the problems arising in a study of the continuum are of two general kinds: completeness of observation, and adequacy of diagnostic interpretation. I will make a few comments on these, then turn the meeting over to Oke and Whitney.

The Interpretation of Line Profiles

1977 ◽  
Vol 36 ◽  
pp. 191-215
Author(s):  
G.B. Rybicki
Keyword(s):  
Magnetic Fields ◽  
Atomic Physics ◽  
Velocity Fields ◽  
Spectral Lines ◽  
Inhomogeneous Structure ◽  
The Sun ◽  
Line Profiles ◽  
Physical Phenomena

Observations of the shapes and intensities of spectral lines provide a bounty of information about the outer layers of the sun. In order to utilize this information, however, one is faced with a seemingly monumental task. The sun’s chromosphere and corona are extremely complex, and the underlying physical phenomena are far from being understood. Velocity fields, magnetic fields, Inhomogeneous structure, hydromagnetic phenomena – these are some of the complications that must be faced. Other uncertainties involve the atomic physics upon which all of the deductions depend.

Central kiloparsec of NGC 1326 observed with SINFONI

2020 ◽  
Vol 638 ◽  
pp. A53
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Andreas Eckart ◽  
Françoise Combes ◽  
Persis Misquitta ◽  
...  
Keyword(s):  
Black Hole ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Velocity Fields ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Stellar Content ◽  
Stellar Rotation ◽  
Supermassive Black Hole ◽  
Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

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