Generalized boundary conditions for the S-model kinetic equations basic to +ow in a plane channel

An analytical version of the discrete-ordinates method is used to solve the classical problems of Poiseuille +ow and thermal-creep +ow in a plane channel. The kinetic theory for the rare4ed-gas +ow is based on the S model (a generalization of the BGK model), and in addition to the use of the di9use–specular re+ection model (based on a single accommodation coe:cient) for describing particle scattering from the channel walls, the Cercignani–Lampis model de4ned in terms of normal and tangential accommodation coe:cients is implemented. The established solution is tested numerically, and results for the velocity and heat-+ow pro4les, the particle-+ow rate and the heat-+ow rate thought to be correct to many signi4cant 4gures are reported for various values of the channel width. ? 2001 Elsevier Science Ltd. All rights reserved.