Lattice Boltzmann method at finite Knudsen numbers

A modified lattice Boltzmann model with a stochastic relaxation mechanism mimicking virtual collisions between free-streaming particles and solid walls is introduced. This modified scheme permits to compute plane channel flows in satisfactory agreement with analytical results over a broad spectrum of Knudsen numbers, ranging from the hydrodynamic regime, all the way to quasi-free flow regimes up to Kn similar to 30.