In 1982, the Belgian Pilots' Guild raised the question of what effect exposure to radar radiation--for example, that encountered in passing a pilot launch's radar--might have on the human body. Recapitulating investigations of this question, this article states that in 25 years of experience with radar, there have been no known incidents of pilots being affected by radar waves. In the future, however, involvement by some pilots with Vessel Traffic Service shore-based radar could affect pilots somewhat differently from limited exposure to pilot launch radar. Pilots who find themselves in new working conditions close to an emitting source should exercise care all times.

About heat waves

In the preceding chapters with few exceptions we studied systems at equilibrium. This means that the systems do not change or evolve over time.

Non-Equilibrium Thermodynamics

Der vorliegende Band enthált sechs Beitrage, in denen punktuell und exemplarisch der Stand der Forschung beleuchtet wird. Ein Beitrag von Codling und Frasinski beschreibt in erster Linie Experimente zum noch wenig verstandenen Phânomen der dissoziativen Ionisation von Molekülen, bei dem diese in einem intensiven Laserfeld mehrere Elektronén verlieren und in Ionen mit hoher kinetischer Energie zerfallen. Ein wesentlicher Teil dieses Beitrags widmet sich einer von den Autoren entwickelten Auswertungstechnik, welche die Korrelationen zwischen den Fiugzeiten emittierter Ionen und Elektronén sichtbar macht. Es folgen drei Beitrage zur Théorie. Schmelcher und Cederbaum beschreiben Effekte starker statischer Felder, die nur dann zu verstehen sind, wenn die Nicht-Separation der Schwerpunktsbewegung im auBeren Magnetfeld korrekt beriicksichtigt wird. Dies fiihrt

Extended Irreversible Thermodynamics

Numerical simulation and theoretical analysis based on a model Boltzmann equation show that a plane shock wave in a polyatomic gas with large bulk viscosity exhibits three different types of structure, depending on the upstream Mach number.

Shock-wave structure for a polyatomic gas with large bulk viscosity

ABSTRACT To resolve the discrepancy between the numerical detonation cell size and experimental observations, simulations are conducted with a detailed thermochemical reaction model for a premixed argon-diluted hydrogen-oxygen mixture. Four different scenarios are considered: (i) The whole system is in thermodynamic equilibrium; (ii) the vibrational relaxation is considered and the translational-rotational temperature is used as the dominant temperature of the chemical reactions; (iii) the same non-equilibrium effect as in the second scenario is used along with Park’s two-temperature model to account for the effect of vibrational temperature on chemical reaction rates; and (iv) a more physically consistent vibration-chemistry-vibration coupling model is adopted. The simulated detonation cell widths for the first and second scenarios are significantly lower than the experimental measurements, whereas reasonable agreement is observed for the third and fourth scenarios. These results confirm that the involvement of vibrational relaxation in the chemical reactions is an important mechanism in gaseous detonation.

/pdf/assessment-of-vibrational-non-equilibrium-effect-on-4bisabec5g.pdf

Assessment of vibrational non-equilibrium effect on detonation

The paper discusses the shock structure in macroscopic multi-temperature model of gaseous mixtures, recently established within the framework of extended thermodynamics. The study is restricted to weak and moderate shocks in a binary mixture of ideal gases with negligible viscosity and heat conductivity. The model predicts the existence of temperature overshoot of heavier constituent, like more sophisticated approaches, but also puts in evidence its non-monotonic behavior not documented in other studies. This phenomenon is explained as a consequence of weak energy exchange between the constituents, either due to large mass difference, or large rarefaction of the mixture. In the range of small Mach number it is also shown that shock thickness (or equivalently, the inverse of Knudsen number) decreases with the increase of Mach number, as well as when the mixture tends to behave like a single-component gas (small mass difference and/or presence of one constituent in traces).

Shock structure and temperature overshoot in macroscopic multi-temperature model of mixtures

In this paper we make a comparison between numerically calculated shock profiles for He-Ar mixture and experimental data. We use a macroscopic model derived within the framework of extended thermodynamics with a multi-temperature assumption. Theoretically predicted velocity profiles are in good agreement with experimental data. Temperature profiles capture satisfactorily the overall tendency, although certain discrepancies are observed which also appeared in other more sophisticated theoretical models.

http://iopscience.iop.org/article/10.1209/0295-5075/102/44002/pdf

Shock structure in helium-argon mixture —A comparison of hyperbolic multi-temperature model with experiment

This paper is concerned with the analysis of polyatomic gases within the framework of kinetic theory. Internal degrees of freedom are modelled using a single continuous variable corresponding to the molecular internal energy. The state of the gas is determined by the 6 fields—5 standard fields (mass density, velocity and temperature) and the dynamic pressure. Using the maximum entropy principle and the non-equilibrium entropy density, it is shown that dynamic pressure appears as a natural measure for deviation from equilibrium state. A proper collision cross section is constructed which obeys the micro-reversibility requirement. The non-linear source term in the balance law for dynamic pressure, and the entropy production rate, are determined using collision operator in the form which generalizes the known results obtained within the framework of extended thermodynamics. They are also compared with the results obtained using BGK approximation. For the proposed model the shock structure problem is thoroughly analyzed and discussed for different values of the parameters in the source term.

Polyatomic gases with dynamic pressure: Kinetic non-linear closure and the shock structure

Limits of classical constitutive laws such as Fourier and Navier–Stokes equations are discovered since decades. However, the proper extensions—generalizations of these—are not unique. They differ in the underlying physical principles and in modeling capabilities. In this paper, two different theories are discussed and compared to each other, namely the kinetic theory-based rational extended thermodynamics (RET) and non-equilibrium thermodynamics with internal variables (NET-IV). First, the paper starts with the case of rigid heat conductors summarizing the result achieved so far. Then, a typical example of compressible bodies is shown by presenting the first generalization for rarefied gases, called Meixner’s theory. It is further extended using generalized entropy current in the framework of NET-IV. It is shown how its structure is related to RET and how the compatibility between them can be acquired.

/pdf/non-equilibrium-theories-of-rarefied-gases-internal-3a4xhebhx8.pdf

Non-equilibrium theories of rarefied gases: internal variables and extended thermodynamics

Limits of classical constitutive laws such as Fourier and Navier-Stokes equations are discovered since decades. However, the proper extensions - generalizations of these are not evident. They differ in the underlying physical principles and in modeling capabilities. In this paper, two different theory is discussed and compared to each other, namely the kinetic theory based Rational Extended Thermodynamics (RET) and non-equilibrium thermodynamics with internal variables (NET-IV). 
First, the paper starts with the case of rigid heat conductors summarizing the result achieved so far. Then a typical example of compressible bodies is shown by presenting the first generalization for rarefied gases, called Meixner's theory. It is further extended using generalized entropy current in the framework of NET-IV. It is shown how its structure is related to RET and how the compatibility between them can be acquired.

Damir Madjarević

Papers

Shock structure and temperature overshoot in macroscopic multi-temperature model of mixtures

Shock structure in helium-argon mixture —A comparison of hyperbolic multi-temperature model with experiment

Polyatomic gases with dynamic pressure: Kinetic non-linear closure and the shock structure

Non-equilibrium theories of rarefied gases: internal variables and extended thermodynamics

Theories of rarefied gases