Comparisons of Measured and Predicted Velocity Distribution Functions in a Shock Wave

Molecular velocity distribution functions measured in a normal shock wave in helium at M = 1.59 show deviations from equilibrium which are consistent in functional form, but not quantitatively, with the deviations predicted by the Chapman-Enskog first iterate. The measurements do appear to be in substantial agreement with a Monte Carlo solution of the Boltzmann equation, as indicated by a comparison of the half-widths of the parallel velocity distributions in the shock wave.