Spectral Modeling of Radiative Heat Transfer in Carbonaceous Atmospheres Using New k-Distribution Models and Databases

Multi-scale correlated-k distribution models are presented for the red and violet bands of CN for applications relevant to entry into the atmospheres of Titan, Mars, Venus and flows over an ablating heat shield. In the multi-scale model spectral lines are separated into different scales to improve correlation among absorption coefficients. The methodology for scaling absorption coefficients into such groups is presented. A new emission-weighted full-spectrum k-distribution model is proposed as an improvement over the more popular Planck function-weighted full-spectrum k-distribution model. In the new model, the emission coefficient replaces the Planck-function as weight in the reordering scheme. Accuracies of the two models are compared by solving severe two-cell problems. To exploit the full potential of the k-distribution method databasing schemes for k-distributions are discussed and cpu-time studies are presented. The accuracy of the new model and the database is demonstrated by solving the radiative transfer equation along the stagnation line flow field of the Huygens spacecraft.