Modeling Non-Equilibrium Gas Flows
主 题: Modeling Non-Equilibrium Gas Flows
报告人: Manuel Torrilhon (RWTH Aachen Univeristy)
时 间: 2012-11-07 14:30
地 点: 理科一号楼 1560
Rarefied gas flows, or equally gas micro-flows, exhibit
strong non-equilibrium behavior due to insufficient particle
interactions, that is, the Knudsen number - the ratio between the mean
free path and a macroscopic length - becomes significant. The
traditional equations of gas dynamics with the constitutive laws of
Navier-Stokes and Fourier for stress tensor and heat flux are known to
loose their validity in these situations. Instead the flow needs to be
modeled on the basis of kinetic gas theory and the Boltzmann
equation. However, this statistical approach is computationally
expensive and also can not provide much fluid-dynamic intuition for
the non-equilibrium phenomena.
The regularized 13-moment-equations (R13) extend the classical fluid
dynamic equations for processes with moderate Knudsen numbers. The
system is based on Grad's 13-moment equations known from kinetic gas
theory and extended thermodynamics. We will briefly discuss the
derivation of the equations and their properties like stability,
asymptotic accuracy and entropy. It is also possible to formulate
boundary conditions obtained from kinetic gas theory for the R13
system and we present results for standard internal and external flow
problems, like channel flow and flow past a sphere, which show
interesting non-intuitive features in the rarefied situation.
