Pressure and bulk viscosity in a hard sphere gas

Abstract

The pressure in a dilute hard sphere gas is calculated, starting from the virial theorem and making use of the ergodic hypothesis. The time development of the system is described within the ’’sucessive uncorrelated binary collision approximation.’’ The results obtained are applied to calculate the time correlation function for the bulk viscosity. As is well known, only the potential part of the time correlation function gives a nonvanishing contribution to the bulk viscosity. It is shown that for hard spheres the time correlation function is just a δ function without an exponentially decaying contribution.