#Dynamic light 1.5.2 how to
This research may shed some light on how to choose/develop macroscopic equations for rarefied gas dynamics. Our results show that, among about a dozen tested equations, the regularized 26 moment equations are the most accurate. Rayleigh-Brillouin spectra of the scattered light are calculated by solving the linearised macroscopic equations and compared to those from the linearised Boltzmann equation.
Since the influence of gas-surface interaction is absent, the accuracy assessment of these macroscopic equations is not contaminated by the boundary condition.
We consider the problem of Rayleigh-Brillouin scattering, where light is scattered by the density fluctuation of gas molecules. This paper is dedicated to assess the accuracy of these macroscopic equations that have the potential to be applied in the study of aerodynamics of rarefied gases.
Many macroscopic equations are proposed to describe the rarefied gas dynamics beyond the Navier-Stokes level, either from the mesoscopic Boltzmann equation or some physical arguments, including (1) Burnett, Woods, super-Burnett, augmented Burnett equations derived from the Chapman-Enskog expansion, (2) Grad 13, regularized 13/26 moment equations, rational extended thermodynamics equations, and generalized hydrodynamic equations, where the velocity distribution function is expressed in terms of some low-order moments and Hermite polynomials, and (3) bi-velocity equations and thermo-mechanically consistent Burnett equations based on the argument of volume diffusion.
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