Effects of Long‐Lived Collisions in the Boltzmann Equation

Abstract

The general formulation of transporttheory in gases does not take into account long‐lived collisions or other properties of collision duration and molecular size that become especially important at higher densities. All these properties can be included in the theory in a uniform way by introducing the concept of the collision lifetime in addition to the collision cross section in the derivation of the equations of transporttheory. A formulation of the classical Boltzmann equation is given in which the two‐body collision term containing the collision lifetime explictly appears. In addition, two‐body correction terms reflecting the spatial extension of the collision are derived.