Sound propagation through a binary mixture of rarefied gases at arbitrary sound frequency

• Numerical solution of the McCormack model to the linearized Boltzmann equation.
• Influence of the sound frequency on the macrocharacteristics of binary mixtures.
• Influence of the molecular mass ratio of species on the sound propagation.
• Deviation of the macrocharacteristics of the mixture from those for a single gas.

The sound propagation through a binary mixture of rarefied gases in a semi-infinite space is investigated on the basis of the McCormack model to the linearized Boltzmann equation. The source of sound waves is an infinite and flat plate oscillating in the direction normal to its own plane. It is considered a fully established oscillation so that the solution of the kinetic equation depends on time harmonically. The diffuse scattering gas–surface interaction law is assumed as the boundary condition on the oscillatory plate. A realistic intermolecular potential based on experimental data for the transport coefficients of the mixture is employed in the calculations. Two mixtures of noble gases, namely, Helium–Argon and Helium–Xenon, are considered in order to investigate the influence of the molecular mass ratio of species on the problem. A wide range of the oscillation speed parameter, defined as the ratio of intermolecular collision frequency to sound frequency, is considered. The amplitudes and phases of the macrocharacteristics of the gas flow are calculated and the results are compared to those obtained for a single gas.