Internal Energy Mode Relaxation in High Speed Continuum and Rarefied Flows
Abstract
The presence of shock waves in high speed flow of a polyatomic gas presents considerable difficulties for accurate numerical simulation of the flowfield. The shock wave redistributes the high kinetic energy of the oncoming flow into various internal energy modes, which relax relatively slowly, leading to significant chemical and thermal nonequilibrium the stagnation region. In the gas kinetic description, intermolecular collisions change the translational, rotational, vibrational, and electronic energies of the collision partners. The probabilities or effective cross sections of these elementary processes differ significantly giving rise to widely separate relaxation times for the internal modes. Thus it becomes important to account for the rates of relaxation processes to predict the nonequilibrium behavior of these kinds of flows. The continuum description is well suited at lower altitudes of the flight regime for the prediction of aerodynamic loads and heating rates on the thermal protection systems. However at high altitudes and associated low densities the larger mean free path invalidates the continuum assumption and the rarefied solution approaches are necessary. Among the solution approaches in hypersonic rarefield of Direct Simulation Monte Carlo (DSMC) method is widely used.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 07, 2003
- Accession Number
- ADA414578
Entities
People
- Dean C. Wadsworth
- Eswar Josyula