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Special Issue "Thermodynamics of Non-Equilibrium Gas Flows"

A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Thermodynamics".

Deadline for manuscript submissions: 15 October 2018

Special Issue Editor

Guest Editor
Dr. Xiaojun Gu

Daresbury Laboratory, Scientific Computing Department, Science and Technology Facilities Council (STFC), Warrington WA4 4AD, UK
E-Mail
Interests: combustion; turbulence; rarefied gas dynamics; kinetic theory; extended thermodynamics

Special Issue Information

Dear Colleagues,

Non-equilibrium gas flows exist in many industrial applications and scientific research facilities, including mass spectrometry, low-pressure environments, vacuum pumps, micro-electro-mechanical systems (MEMS), high-altitude vehicles, and porous media. A comprehensive understanding of the thermodynamics of non-equilibrium gas flows is essential for the design and operation of application systems, which are beyond the capabilities of conventional thermodynamics. These flows in engineering applications cover a wide range of time and length scales and represent a fundamental modelling and simulation challenge.

The thermodynamics of non-equilibrium gas flows can be described from either microscopic or macroscopic points of view. Both approaches have their advantages and limitations. Significant progress has been made in terms of physical and mathematical models, numerical algorithms, computational implementations and experimental techniques, which improve our ability to explain the non-equilibrium phenomena to enrich the knowledge of non-equilibrium thermodynamics. Multiscale approaches have been developed to solve the real applications accurately and effectively. 

This Special Issue aims at collecting original papers on theoretical, computational and experimental studies of non-equilibrium, low- and high-speed gas flows with the goal of providing readers with an overview of the current research conducted in this field and the possible applications.

Dr. Xiaojun Gu
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • non-equilibrium
  • kinetic scheme
  • moment method
  • extended thermodynamics
  • rarefied gas dynamics
  • direct simulation Monte Carlo (DSMC)
  • Boltzmann equation
  • spacecraft reentry
  • MEMS
  • vacuum

Published Papers (2 papers)

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Research

Open AccessArticle Evaporation Boundary Conditions for the Linear R13 Equations Based on the Onsager Theory
Entropy 2018, 20(9), 680; https://doi.org/10.3390/e20090680
Received: 17 July 2018 / Revised: 28 August 2018 / Accepted: 3 September 2018 / Published: 6 September 2018
PDF Full-text (5409 KB) | HTML Full-text | XML Full-text
Abstract
Due to the failure of the continuum hypothesis for higher Knudsen numbers, rarefied gases and microflows of gases are particularly difficult to model. Macroscopic transport equations compete with particle methods, such as the Direct Simulation Monte Carlo method (DSMC), to find accurate solutions
[...] Read more.
Due to the failure of the continuum hypothesis for higher Knudsen numbers, rarefied gases and microflows of gases are particularly difficult to model. Macroscopic transport equations compete with particle methods, such as the Direct Simulation Monte Carlo method (DSMC), to find accurate solutions in the rarefied gas regime. Due to growing interest in micro flow applications, such as micro fuel cells, it is important to model and understand evaporation in this flow regime. Here, evaporation boundary conditions for the R13 equations, which are macroscopic transport equations with applicability in the rarefied gas regime, are derived. The new equations utilize Onsager relations, linear relations between thermodynamic fluxes and forces, with constant coefficients, that need to be determined. For this, the boundary conditions are fitted to DSMC data and compared to other R13 boundary conditions from kinetic theory and Navier–Stokes–Fourier (NSF) solutions for two one-dimensional steady-state problems. Overall, the suggested fittings of the new phenomenological boundary conditions show better agreement with DSMC than the alternative kinetic theory evaporation boundary conditions for R13. Furthermore, the new evaporation boundary conditions for R13 are implemented in a code for the numerical solution of complex, two-dimensional geometries and compared to NSF solutions. Different flow patterns between R13 and NSF for higher Knudsen numbers are observed. Full article
(This article belongs to the Special Issue Thermodynamics of Non-Equilibrium Gas Flows)
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Open AccessArticle Stability Analysis on Magnetohydrodynamic Flow of Casson Fluid over a Shrinking Sheet with Homogeneous-Heterogeneous Reactions
Entropy 2018, 20(9), 652; https://doi.org/10.3390/e20090652
Received: 3 August 2018 / Revised: 28 August 2018 / Accepted: 29 August 2018 / Published: 30 August 2018
PDF Full-text (670 KB) | HTML Full-text | XML Full-text
Abstract
Two-dimensional magnetohydrodynamic (MHD) stagnation point flow of incompressible Casson fluid over a shrinking sheet is studied. In the present study, homogeneous-heterogeneous reactions, suction and slip effects are considered. Similarity variables are introduced to transform the governing partial differential equations into non-linear ordinary differential
[...] Read more.
Two-dimensional magnetohydrodynamic (MHD) stagnation point flow of incompressible Casson fluid over a shrinking sheet is studied. In the present study, homogeneous-heterogeneous reactions, suction and slip effects are considered. Similarity variables are introduced to transform the governing partial differential equations into non-linear ordinary differential equations. The transformed equations and boundary conditions are then solved using the bvp4c solver in MATLAB. The local skin friction coefficient is tabulated for different values of suction and shrinking parameters. The profiles for fluid velocity and concentration for various parameters are illustrated. It was found that two solutions were obtained at certain ranges of parameters. Then, the bvp4c solver was used to perform stability analysis on the dual solutions. Based on the results, the first solution was more stable and physically meaningful than the other solution. The skin friction coefficient increased when suction increased, but decreased when the magnitude of shrinking parameter increased. Meanwhile, the velocity and concentration profile increased in the presence of a magnetic field. It is also noted that the higher the strength of the homogeneous-heterogeneous reactions, the lower the concentration of reactants. Full article
(This article belongs to the Special Issue Thermodynamics of Non-Equilibrium Gas Flows)
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