Seminario - Multiscale phenomena in Continuum Mechanics: Mesoscopic justification of Rational Extended Thermodynamics of Gases with internal structure

nell'ambito delle attività del CIMAT, giorno 5 novembre p.v. alle ore
17:00 presso l'aula A.M. Anile il prof. Tommaso Ruggeri
dell'Università di Bologna, terrà un seminario dal titolo

Multiscale phenomena in Continuum Mechanics: Mesoscopic justification
of Rational Extended Thermodynamics of  Gases with internal structure.

Abstract:

In many physical systems one encounters situations where phenomena
occur at different scales.  An example is the modeling of a rarefied
gas at varying Knudsen number (Kn). Large Kn is where Boltzmann
equation is the most appropriate model while, for small Kn, one can
obtain Euler or the Navier-Stojes-Fourier  system. At intermediate
regimes, using the mathematical methods of Rational Extended
Thermodynamics (RET), one can obtain the closure of moments system
associated with the Boltzmann equation considering a distribution
function depending of an extra variable  that take into account the
internal motion of  polyatomic gas (rotation and vibration). In this
talk we consider a more refined version  or RET in which molecular
rotational and vibrational relaxation processes are treated
individually.  In this case we need a triple hierarchy of the moment
system and the system of balance equations is closed via the maximum
entropy principle.  Three different types of the production terms in
the system, which are suggested by a generalized BGK-type collision
term in the Boltzmann equation, are adopted.  In particular, the
rational extended thermodynamic theory with seven independent fields
is analyzed in detail.  Finally, the dispersion relation of ultrasonic
wave is confirmed by the experimental data for several  gases.