In this paper, a theoretical method is presented to calculate Brillouin linewidth (BLW) in gas mixtures. The presented model is based on Newton's viscosity law and the kinetic theory of gases. From a combination of Chapman–Enskog theory and Navier–Stokes mathematical model, we recovered the appropriate terms of the viscosity tensor for gas mixtures. We demonstrated that viscosity is not necessarily the dominant mechanism in the enhancement or suppression of the BLW in a gas mixture, and other parameters, such as density, can be dominant instead. It was found that the contribution of thermodynamics quantities was negligible compared to other parameters. The numerical results were also compared to those obtained from the molar refraction-mixing method and confirmed that these results were completely coherent.

本文提出了一种理论方法来计算混合气体中的布里渊线宽（BLW）。提出的模型基于牛顿的粘度定律和气体动力学理论。通过结合Chapman–Enskog理论和Navier–Stokes数学模型，我们获得了混合气体粘度张量的适当项。我们证明了粘度不一定是混合气体中BLW增强或抑制的主要机理，而其他参数（例如密度）也可以占主导地位。发现与其他参数相比，热力学量的贡献可忽略不计。还将数值结果与通过摩尔折射混合法获得的结果进行比较，并证实这些结果是完全一致的。