Moment method and non-equilibrium thermodynamics of rarefied gas mixture

2012 ◽  
Author(s):  
Vladimir M. Zhdanov ◽  
Vjacheslav I. Roldughin
Keyword(s):  
Moment Method ◽  
Rarefied Gas ◽  
Gas Mixture ◽  
Equilibrium Thermodynamics ◽  
Non Equilibrium

scholarly journals Formulation of moment equations for rarefied gases within two frameworks of non-equilibrium thermodynamics: RET and GENERIC

2020 ◽  
Vol 378 (2170) ◽  
pp. 20190174 ◽  
Author(s):  
Hans Christian Öttinger ◽  
Henning Struchtrup ◽  
Manuel Torrilhon
Keyword(s):  
Rarefied Gas ◽  
Practical Importance ◽  
Irreversible Processes ◽  
Moment Equations ◽  
Equilibrium Thermodynamics ◽  
Generic Structure ◽  
New Strategy ◽  
The Moment ◽  
Rational Extended Thermodynamics ◽  
Non Equilibrium

In this work, we make a further step in bringing together different approaches to non-equilibrium thermodynamics. The structure of the moment hierarchy derived from the Boltzmann equation is at the heart of rational extended thermodynamics (RET, developed by Ingo Müller and Tommaso Ruggeri). Whereas the full moment hierarchy has the structure expressed in the general equation for the nonequilibrium reversible–irreversible coup- ling (GENERIC), the Poisson bracket structure of reversible dynamics postulated in that approach is a major obstacle for truncating moment hierarchies, which seems to work only in exceptional cases (most importantly, for the five moments associated with conservation laws). The practical importance of truncated moment hierarchies in rarefied gas dynamics and microfluidics motivates us to develop a new strategy for establishing the full GENERIC structure of truncated moment equations, based on non-entropy-producing irreversible processes associated with Casimir symmetry. Detailed results are given for the special case of 10 moments. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.

scholarly journals Analysis of the Moment Method and the Discrete Velocity Method in Modeling Non-Equilibrium Rarefied Gas Flows: A Comparative Study

2019 ◽  
Vol 9 (13) ◽  
pp. 2733
Author(s):  
Weiqi Yang ◽  
Shuo Tang ◽  
Hui Yang
Keyword(s):  
Moment Method ◽  
Rarefied Gas ◽  
Hermite Polynomials ◽  
Distribution Functions ◽  
Gas Flows ◽  
Thermally Induced ◽  
Rarefied Gas Flows ◽  
Discrete Velocity Method ◽  
The Moment ◽  
Non Equilibrium

In the present study, the performance of the moment method, in terms of accuracy and computational efficiency, was evaluated at both the macro- and microscopic levels. Three different types of non-equilibrium gas flows, including the force-driven Poiseuille flow, lid-driven and thermally induced cavity flows, were simulated in the slip and transition regimes. Choosing the flow fields obtained from the Boltzmann model equation as the benchmark, the accuracy and validation of Navier–Stokes–Fourier (NSF), regularized 13 (R13) and regularized 26 (R26) equations were explored at the macroscopic level. Meanwhile, we reconstructed the velocity distribution functions (VDFs) using the Hermite polynomials with different-order of molecular velocity moments, and compared them with the Boltzmann solutions at the microscopic level. Moreover, we developed a kinetic criterion to indirectly assess the errors of the reconstructed VDFs. The results have shown that the R13 and R26 moment methods can be faithfully used for non-equilibrium rarefied gas flows in the slip and transition regimes. However, as indicated from the thermally induced case, all of the reconstructed VDFs are still very close to the equilibrium state, and none of them can reproduce the accurate VDF profile when the Knudsen number is above 0.5.

scholarly journals Application of non-equilibrium plasmas in medicine

2012 ◽  
Vol 77 (12) ◽  
pp. 1689-1699 ◽  
Author(s):  
Zoran Petrovic ◽  
N. Puac ◽  
G. Malovic ◽  
S. Lazovic ◽  
D. Maletic ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Medical Applications ◽  
Gas Mixture ◽  
Oxygen Species ◽  
Special Issue ◽  
Plasma Sources ◽  
Volatile Organic ◽  
Plasma Needle ◽  
Group A ◽  
Non Equilibrium

We review the potential of plasma medical applications, the connections to nanotechnologies and the results obtained by our group. A special issue in plasma medicine is the development of the plasma sources that would achieve non-equilibrium at atmospheric pressure in atmospheric gas mixture with no or only marginal heating of the gas, and with desired properties and mechanisms that may be controlled. Our studies have shown that control of radicals or chemically active products of the discharge such as ROS (reactive oxygen species) and/or NO may be used to control the growth of the seeds. At the same time specially designed plasma needle and other sources were shown to be efficient to sterilize not only colonies of bacteria but also planctonic samples (microorganisms protected by water) or bio films. Finally we have shown that plasma may induce differentiation of stem cells. Non-equilibrium plasmas may be used in detection of different specific markers in medicine. For example proton transfer mass spectroscopy may be employed in detection of volatile organic compounds without their dissociation and thus as a technique for instantaneous measurement of the presence of markers for numerous diseases.

scholarly journals Contraction of polymer gels created by the activity of molecular motors

Soft Matter ◽  
2019 ◽  
Vol 15 (22) ◽  
pp. 4467-4475 ◽  
Author(s):  
Mattia Bacca ◽  
Omar A. Saleh ◽  
Robert M. McMeeking
Keyword(s):  
Mechanical Behavior ◽  
Molecular Motors ◽  
Polymer Gels ◽  
Polymer Gel ◽  
Equilibrium Thermodynamics ◽  
Non Equilibrium

We propose a theory based on non-equilibrium thermodynamics to describe the mechanical behavior of an active polymer gel created by the inclusion of molecular motors in its solvent.

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