  In the present study, soot formation in the turbulent lifted diffusion flame,
consisting of ethylene-air is numerically investigated using three different
soot modeling approaches and is comprehensively reported. For
turbulence-chemistry interaction, Flamelet generated manifold (FGM) model is
used. A detailed kinetics is used which is represented through POLIMI mechanism
(Ranzi et al. 2012). Soot formation is modeled using two different approaches,
semi-empirical two-equation approach and Quadrature methods of moments
approach, where both the approaches consider various sub-processes such as
nucleation, coagulation, surface growth and oxidation. The radiation heat
transfer is taken into account considering four fictitious gasses in
conjunction with the weighted-sum-of-gray gas (WSSGM) approach for modeling
absorption coefficient. The experimental and earlier published numerical data
from K\"ohler et al. (2012) and Blacha et al. (2011) are used for assessment of
different soot modeling approaches. The discrepancies between numerical and
experimental data are observed due to under-prediction of OH radicals
concentration and poor fuel-air mixing ratios in the vicinity of the fuel jet
region leading to early soot formation and the trends are unaffected after
invoking radiation.
