Abstract
Mathematical consideration is given to the symmetry of free molecular flows through the pipe of an arbitrary shape. In the previous paper (I), it was shown that the diffuse reflection based on a stochastic model conserves the symmetry if and only if it obeys cosine law. To explore whether a specular reflection conserves the symmetry, a new framework including both the stochastic and deterministic models was developed. Using this unified framework it immediately follows that the specular reflection conserves the symmetry, even when arbitrarily mixed with the cosine law reflection. In contrast with the stochastic model, the deterministic model allows innumerable symmetry-preserving reflection rules.
