Mean-Free-Path Definition in the Mott-Smith Shock Wave Solution

The bimodal analysis of Mott-Smith yields a reciprocal shock thickness, reduced by a mean free path ahead of the shock, that tends to zero for various intermolecular laws of force with increasing shock strength, yet remains finite for rigid-sphere molecules. It is shown that the introduction of a center of shock mean free path, self-consistent within the bimodal solution, results in finite reciprocal thicknesses for such diverse laws of interaction as inverse fifth and rigid-sphere molecules. When reduced by a center of shock mean free path, the reciprocal thickness is not too sensitive to the particular law of molecular interaction.