DIVERGENT TRANSPORT COEFFICIENTS AND THE BINARY COLLISION EXPANSION

摘要

The binary collision expansion expression for the viscosity of a two dimensional gas of hard disks has been discussed in detail. We have found a divergence in n1 the first correction to the Boltzmann equation result. The physical origin of the divergence is precisely the same as that found by Dorfman and Cohen from phase space estimates and by Sengers from an exact calculation of n1, using the Choh-Uhlenbeck formalism. Furthermore, we have demonstrated the precise numerical agreement of the coefficient of the divergence, as obtained by us from the binary collision expansion, with that obtained by Sengers from the Bogoliubov theory. It must be concluded, therefore, that a divergence does indeed appear in the density expansion of transport coefficients.