Treatment of laser-induced thermal acoustics in the framework of discrete kinetic theory

The physics behind the laser-induced thermal acoustics technique is dealt w ith on a microscopic level. A discrete velocity model of the Boltzmann equa tion for inelastically interacting gas mixtures in the presence of two coun terpropagating laser beams is established. The collisional scheme for the m odel is developed by taking into account elastic and inelastic interactions between the gas particles, on the one hand, and the interactions between m onochromatic laser photons and gas particles, on the other hand. The format ion and evolution of laser-pulse-driven thermal and density gratings are si mulated by numerically solving the discrete kinetic equations based on the fractional step method. Numerical results are provided for a wide scope of Knudsen numbers.