Among the three heat conduction modes (diffusive, second sound, and ballistic propagation), the ballistic one is the most difficult to model. In the present paper, we discuss its physical interpretations and show different alternatives to its modelling. We highlight two of them: a thermo-mechanical model in which the generalized heat equation—the so-called Maxwell–Cattaneo–Vernotte equation—is coupled to thermal expansion. The other one uses internal variables in the framework of non-equilibrium thermodynamics. For the first one, we developed a numerical solution and tested it on the heat pulse experiment performed by McNelly et al. on NaF samples. For the second one, we found an analytical solution that emphasizes the role of boundary conditions. This analytical method is used to validate an earlier developed numerical code.

在三种导热模式（扩散，第二声音和弹道传播）中，弹道之一是最难建模的。在本文中，我们讨论了其物理解释，并显示了其建模的不同选择。我们重点介绍其中的两个：热力学模型，其中广义的热方程式-所谓的麦克斯韦-卡塔尼奥-维诺特方程式-与热膨胀耦合。另一类在非平衡热力学框架内使用内部变量。对于第一个，我们开发了一个数值解决方案，并在McNelly等人进行的热脉冲实验中进行了测试。在NaF样品上。对于第二个问题，我们找到了强调边界条件作用的分析解决方案。此分析方法用于验证较早开发的数字代码。