부산대학교 도서관

The authors give a simple recipe to derive discrete velocity models from the (continuous velocity) Boltzmann equation. Plane discrete models are tested, in the spatially homogeneous case, by comparing their numerical solutions with the closed form solutions proposed by M. Krook and T. T. Wu [Phys. Rev. Lett. {\bf 36} (1976), no. 19, 1107--1109] and M. H. Ernst\ [Phys. Rep. {\bf 78} (1981), no.~1, 1--171; MR0636604 (84c:82016)]. The solutions of the discrete models present two shortcomings: (a) they cannot preserve isotropy; (b) the average relaxation to equilibrium is remarkably slower than predicted by the Boltzmann equation.