Soot formation modelling for n-dodecane sprays using the transported PDF model

The experimental comparisons for soot consider transient soot mass and KL in the baseline condition, and steady state soot volume fraction (SVF) fields and total soot masses for all five ambient conditions. In terms of comparisons to experiment, the transient stage of the soot mass development is not well captured. An analysis of the transient KL in the baseline case shows the soot-containing region is larger in the experiment than the model, with soot extending in the experiment much closer to the jet boundary, suggesting that the model underestimates gradients around the jet head. During the steady period, however, the SVF agrees quite well. The soot models with both chemistry and TCI approaches were able to reproduce the overall soot trends with varying ambient temperature and oxygen, though the effect of the ambient temperature on the soot mass was under-predicted, in particular in its variation from 900 to 1000 K. TCI effects on soot were in overall terms relatively minor, in part due to compensating errors. Neglecting TCI showed generally higher peak soot amounts, narrower soot distributions, and more downstream soot onset and soot peak locations. These differences between the models are explained with the help of a detailed analysis of the soot phenomena.