Direct simulation Monte Carlo simulation of thermal fluctuations in gases

Work done by the authors on the Direct Simulation Monte Carlo (DSMC) simulation of thermal fluctuation in gases is summarized here. The calculation of the gas transport properties via the Green-Kubo formulas is discussed. Results from classical trajectory DSMC simulations of molecular oxygen show how the approach can be used to validate a particular interaction model (a Potential Energy Surface in this case). Direct experimental validation of the dynamics of spontaneous density fluctuations is also possible due to its connection to the spectrum measured in Rayleigh-Brillouin light scattering experiments (RBS). A number of examples of the DSMC simulation of RBS spectra for atomic gases and their mixtures, and for a molecular gas (oxygen) are discussed. Finally, an extension of the method is discussed that allows discussion of small density-dependent nonideality effects in the RBS spectra of SF6. Published under license by AIP Publishing.