Shock Front Thickness and Bulk Viscosity in Polyatomic Gases

1956 ◽  
Vol 24 (4) ◽  
pp. 767-770 ◽  
Author(s):  
W. H. Andersen ◽  
D. F. Hornig
Keyword(s):  
Shock Front ◽  
Bulk Viscosity ◽  
Polyatomic Gases

scholarly journals Relativistic Rational Extended Thermodynamics of Polyatomic Gases with a New Hierarchy of Moments

Entropy ◽  
2021 ◽  
Vol 24 (1) ◽  
pp. 43
Author(s):  
Takashi Arima ◽  
Maria Cristina Carrisi ◽  
Sebastiano Pennisi ◽  
Tommaso Ruggeri
Keyword(s):  
Bulk Viscosity ◽  
Maximum Entropy Principle ◽  
Entropy Density ◽  
Extended Thermodynamics ◽  
Bgk Model ◽  
Rest Energy ◽  
Polyatomic Gases ◽  
The Cauchy Problem ◽  
Entropy Principle ◽  
Rational Extended Thermodynamics

A relativistic version of the rational extended thermodynamics of polyatomic gases based on a new hierarchy of moments that takes into account the total energy composed by the rest energy and the energy of the molecular internal mode is proposed. The moment equations associated with the Boltzmann–Chernikov equation are derived, and the system for the first 15 equations is closed by the procedure of the maximum entropy principle and by using an appropriate BGK model for the collisional term. The entropy principle with a convex entropy density is proved in a neighborhood of equilibrium state, and, as a consequence, the system is symmetric hyperbolic and the Cauchy problem is well-posed. The ultra-relativistic and classical limits are also studied. The theories with 14 and 6 moments are deduced as principal subsystems. Particularly interesting is the subsystem with 6 fields in which the dissipation is only due to the dynamical pressure. This simplified model can be very useful when bulk viscosity is dominant and might be important in cosmological problems. Using the Maxwellian iteration, we obtain the parabolic limit, and the heat conductivity, shear viscosity, and bulk viscosity are deduced and plotted.

scholarly journals Rational extended thermodynamics of dense polyatomic gases incorporating molecular rotation and vibration

2020 ◽  
Vol 378 (2170) ◽  
pp. 20190176 ◽  
Author(s):  
Takashi Arima ◽  
Tommaso Ruggeri ◽  
Masaru Sugiyama
Keyword(s):  
Bulk Viscosity ◽  
Rarefied Gas ◽  
Molecular Rotation ◽  
Extended Thermodynamics ◽  
Molecular Vibration ◽  
Duality Principle ◽  
Linear Wave ◽  
Polyatomic Gases ◽  
Dense Gases ◽  
Rational Extended Thermodynamics

The paper aims to construct a rational extended thermodynamics (RET) theory of dense polyatomic gases by taking into account the experimental evidence that the relaxation time of molecular rotation and that of molecular vibration are quite different from each other. For simplicity, we focus on gases with only one dissipative process due to bulk viscosity. In fact, in some polyatomic gases, the effect of bulk viscosity is much larger than that of shear viscosity and heat conductivity. The present theory includes the previous RET theory of dense gases with six fields as a particular case, and it also includes the RET theory of rarefied polyatomic gases with seven fields in the rarefied-gas limit. The closure is carried out by using the universal principles, that is, Galilean invariance and objectivity, entropy principle, and thermodynamic stability (convexity of entropy), where the duality principle connecting rarefied gases to dense gases also plays an important role. A detailed discussion is devoted to the expression of the production terms in the system of balance equations. As typical examples, we study a gas with virial equations of state and a van der Waals gas. Lastly the dispersion relation of a linear wave is derived, and its comparison with experimental data is made. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

scholarly journals Unusual enhancement of ~ 30 MeV proton flux in an ICME sheath region

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Mitsuo Oka ◽  
Takahiro Obara ◽  
Nariaki V. Nitta ◽  
Seiji Yashiro ◽  
Daikou Shiota ◽  
...  
Keyword(s):  
Shock Front ◽  
Energetic Particle ◽  
Leading Edge ◽  
Solar Energetic Particle ◽  
Interplanetary Shock ◽  
Proton Event ◽  
Sheath Region ◽  
Time Profiles ◽  
Energetic Particle Flux ◽  
Mev Protons

AbstractIn gradual Solar Energetic Particle (SEP) events, shock waves driven by coronal mass ejections (CMEs) play a major role in accelerating particles, and the energetic particle flux enhances substantially when the shock front passes by the observer. Such enhancements are historically referred to as Energetic Storm Particle (ESP) events, but it remains unclear why ESP time profiles vary significantly from event to event. In some cases, energetic protons are not even clearly associated with shocks. Here, we report an unusual, short-duration proton event detected on 5 June 2011 in the compressed sheath region bounded by an interplanetary shock and the leading edge of the interplanetary CME (or ICME) that was driving the shock. While < 10 MeV protons were detected already at the shock front, the higher-energy (> 30 MeV) protons were detected about four hours after the shock arrival, apparently correlated with a turbulent magnetic cavity embedded in the ICME sheath region.

Reflectivity of a 5.8 kbar shock front in water

1981 ◽  
Vol 74 (12) ◽  
pp. 6864-6866 ◽  
Author(s):  
Paul Harris ◽  
Henri Nöel Presles
Keyword(s):  
Shock Front
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