Spherical harmonics method applied to the multi-dimensional radiation transfer

The spectral radiation transfer equation in 2D axisymmetrical and 3D geometries is solved by the P1-approximation of the spherical harmonics and ray-tracing methods. Martian atmosphere and typical entry conditions are considered. Navier–Stokes equations coupled with the nonequilibrium vibrational excitation and finite rate chemistry describe thermodynamically and chemically nonequilibrium gas. The multi-group model is used to model optical properties of CO2–N2 mixture. The developed methodology of integration of the P1-approximation on unstructured grids and subsequent numerical solution allow us to reach reasonable agreement with the accurate ray-tracing method and drastically reduce the cost of solution of the radiation transfer equation in multi-dimensional geometries.