Charles University Chapter of SIAM

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Moment equations for a polytropic gas reproducing adjustable transport coeffcients

Kdy: 02/03/2022 17:00 - 02/03/2022 18:30
Kde: Online via Zoom

We cordially invite you to our next SIAM SC seminar. The talk will be given by Vladimir Djordjić (RWTH Aachen University). See the abstract and poster below:

In this talk we will consider the kinetic model of continuous type describing a polyatomic gas in the non-weighted

setting. Such a model introduces a single continuous variable supposed to capture all the phenomena related to the

more complex structure of a polyatomic molecule. For the complete polyatomic collision operator we propose a

convex combination of purely polyatomic (nonfrozen) and frozen collisions. Motivated by recently proven rigorous

existence and uniqueness result in the space homogeneous case, we use the cross section proposed in that analysis and

establish macroscopic models. In order to see contribution of frozen collisions and moment hierarchy, we compute

relaxation times and transport coecients in a linearized setting for fourteen and seventeen moments system. Then,

in the case of seventeen moments with included frozen collision show both matching with the experimental data for

dependence of the shear viscosity upon temperature and agreement with the theoretical value of Prandtl number given

by the Eucken formula. Finally, we conclude that higher order system together with frozen collisions gives more

adjustable transport coecients.

In addition, the consistency with the monatomic case is achieved by properly rescaling the collision frequency.

poster