Models for non-equilibrium flows in real shock tubes

The shock tube is very well suited for the study of relaxation processes which occur in connection with nonequilibrium flows. It is pointed out that a model for nonequilibrium flow through the relaxation zone of a shock wave has two main elements, including the nonequilibrium flow equations and a description of the (microscopic) chemical reactions. Theoretically, it is not difficult to formulate the problem. However, in view of real computers, the amount of information employed in devising a model of the nonequilibrium flow has to be reduced. The mathematical relations used to describe the processes in nonequilibrium flows are discussed, and real shock tube effects are examined. Attention is given to boundary layers, shock attenuation, and residual impurities in the test section. Computational problems are considered along with some additional physical processes.