Soot inception and Subsequent aggregation, surface growth and oxidation are described through a new pseudo-bivariate population balance model solved with the direct quadrature method of moments (DQMOM) and implemented in a commercial computational fluid dynamics (CFD) code. This modelling strategy, that in this work is presented in its Reynolds-averaged Navier-Stokes (RANS) equation formulation, has the advantage, over conventional approaches based on the solution of a single transport equation for the soot volume fraction, to overcome the assumption of mono-dispersed soot particle size distribution. On the contrary the pseudo-bivariate approach presented in this work is able to represent the evolution of the soot particle size distribution with good accuracy and affordable computational costs. especially when compared with other multi-variate formulations previously developed. This new pseudo-bivariate model is firstly formulated and presented. then predictions obtained with different soot inception models are compared with some recent experimental data from the literature and the role played by the different phenomena involved (e.g., turbulence, oxidation and radiation) is investigated. (C) 2008 Elsevier Ltd. All rights reserved.