In this paper, we use a kind of singular perturbation method to find the normal solution of the Boltzmann equation with small Knudsen number. It is proved that the secular terms may be removed by improving the Hilbert expansion and Enskog expansion.

• 本文用奇异扰动方法讨论了具有小Knudsen数的Boltzmann方程的正规解,证明把Hil-bert展开和Enskog展开加以改进可以消除久期项。