Molecular velocity distribution functions in an argon normal shock wave at Mach number 7

The streamwise and normal moments of molecular velocity distribution functions throughout an argon normal shock wave have been measured in a Mach number 7.18 wind tunnel flow, and the experimental data have been compared with several analytical and numerical solutions. In the experiments, the molecular population distributions parallel and perpendicular to the direction of flow were derived using a Fabry–Perot etalon to resolve the Doppler shifts in electron-beam-stimulated fluorescence of the gas atoms. Predictions from Monte Carlo techniques give close agreement with the details of the experimental nonequilibrium distribution function contours. Bimodal Maxwellian and ellipsoidal functional forms show only general agreement with overall profile breadth.