TABLE OF CONTENTS For low densities and high velocities, the molecular reaction rates within a fluid element do not keep pace with the rapid flow changes. In consequence, internal molecular energy modes, chemical dissociation, species ionization, and molecular radiation are all out of equilibrium. This essential nonequilibrium character complicates extensively the numerical computation of flowfields. It also has a significant impact on the relative roles of computation and experimentation in the vehicle design process.
From the National Academy of Sciences Report Current Capabilities and Future Directions in Computational Fluid Dynamics, 1986
The preceding chapter dealt with high-temperature flows through shock waves, nozzles, over cones, and over blunt-nosed bodies assuming local thermodynamic and chemical equilibrium. In the present chapter, we look at some of the same flows, but assuming local thermodynamic and chemical nonequilibrium. Does it make a difference? You bet your life it does. Nonequilibrium conditions change some of the basic physical characteristics of the flow. Oblique shock waves that you think should be straight become bent. The flow at the throat of a supersonic nozzle is no longer at Mach 1. The speed of sound now depends on the frequency of the sound waves. The surprises continue. Moreover, the calculation of nonequilibrium flows is mathematically completely different from that of an equilibrium flow. They say that variety is the spice of life. Compared to the preceding chapter, the present chapter provides plenty of variety. This is exciting stuff. So sit back and enjoy.
For a given...
