A characteristics approach to radiative gasdynamics

Abstract

Since the equations which govern unsteady radiative gasdynamics are hyperbolic, general situations are treated with a numerical method of characteristics. Upstream absorption of shock layer radiation is included, and it is shown that only Mark radiation boundary conditions are appropriate to a PI differential approximation of one-dimensional radiative fields. Flowfields generated by pistons inserted into ideal gases with arbitrary absorption properties are investigated with use of both the differential approximation and the transfer equation. Results show that the differential approximaton predicts surface pressures and heat-transfer rates accurately. Nonmonotonic surface pressure histories are noted, and it is observed that variations in surface emissivity and temperature may alter vorticity generation rates. Upstream absorption can be a dominant mechanism in flowfield evolution, and in certain cases the effects of radiation upon pressure and velocity may be comparable to those upon temperature.