DIRECT SIMULATION OF DIATOMIC GASES USING THE GENERALIZED HARD-SPHERE MODEL

The generalized hard sphere model that incorporates the effects of attraction and repulsion is examined. First, the model is used to study simple adiabatic heat baths. Then, it is used to predict now measurements in tests involving extremely low freestream temperatures. For the two cases considered, a Mach 26 nitrogen shock and a Mach 20 nitrogen flow over a flat plate, only rotational excitation is deemed important, and appropriate modifications for the Borgnakke-Larsen procedure are developed. In general, for the cases considered, the present model showed a modest improvement over the variable hard sphere model.