Extraction of the translational Eucken factor from light scattering by molecular gas
arXiv:1911.08931 · doi:10.1017/jfm.2020.568
Abstract
Although the thermal conductivity of molecular gases can be measured straightforwardly and accurately, it is difficult to experimentally determine its separate contributions from the translational and internal motions of gas molecules. Yet this information is critical in rarefied gas dynamics as the rarefaction effects corresponding to these motions are different. In this paper, we propose a novel methodology to extract the translational thermal conductivity (or equivalently, the translational Eucken factor) of molecular gases from the Rayleigh-Brillouin scattering (RBS) experimental data. From the numerical simulation of the \cite{LeiJFM2015} model we find that, in the kinetic regime, in addition to bulk viscosity, the RBS spectrum is sensitive to the translational Eucken factor, even when the total thermal conductivity is fixed. Thus it is not only possible to extract the bulk viscosity, but also the translational Eucken factor of molecular gases from RBS light scattering spectra measurements. Such experiments bear the additional advantage that gas-surface interactions do not affect the measurements. For the first time, bulk viscosities (due to the rotational relaxation of gas molecules only) and translational Eucken factors of N2, CO2 and SF6 are simultaneously extracted from RBS experiments.
References in corpus (7)
- Can we find steady-state solutions to multiscale rarefied gas flows within dozens of iterations?
- Temperature-dependent bulk viscosity of nitrogen gas determined from spontaneous Rayleigh-Brillouin scattering
- Bulk viscosity of CO from Rayleigh-Brillouin lightscattering spectroscopy at 532 nm
- Rayleigh-Brillouin scattering of carbon dioxide
- A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths
- Rayleigh-Brillouin scattering in SF in the kinetic regime
- Rayleigh-Brillouin light scattering spectroscopy of nitrous oxide (NO)