FRONTIERS IN COMPUTATIONAL ASTROPHYSICS

Particle and Flames in Radiative and Magnetic Flows

October 11-15, 2010
Lyon, France

Contribution of Manuel Torrilhon

Title

Coarse-Graining in Kinetic Gas Theory: Non-Equilibrium Fluid Flow Models

Topics

"Planetary atmospheric circulation"

Keywords

Kinetic Gas Theory, Boltzmann Equation, Moment Approximations, Regularized 13-Moment-Equations

Abstract

In rarefied gases the assumption of thermal equilibrium is not valid to to insufficient number of particle collisions. Hence, they require special constitutive relations as classical fluid dynamics fails due to the non-equilibrium. This talk will present a new set of partial differential equations for fluid dynamic variables that replaces the system of Navier-Stokes and Fourier in case of significant but moderate non-equilibrium. Main advantage is efficiency compared to direct simulations or particle codes, but also the possibility to gain intuitive insight into non-equilibrium processes. The new system, called Regularized 13-Moment-Equations, is derived on the basis of kinetic gas theory and Grad's theory of moments. We discuss the derivation of the new model, its structure and present simulation results as well as comparison to experiments and DSMC.

Talk