Transport Theory for a Two-Dimensional Dense Gas

A kinetic theory has been proposed by several authors with the goal of eliminating the divergences which appear in the density expansion in nonequilibrium systems. Here, it is shown that for a two-dimensional simple gas the theory presents a new divergence, resulting from the fact that correlations propagate over long distances as a result of hydrodynamic transport. This divergence is discussed explicitly for a gas model: the Maxwell model. It will be indicated why the kinetic theory for a perfect Lorentz gas does not exhibit this new divergence.