The presented work focuses on the development of a multiscale and multiphysics simulation approach for the prediction of nanoparticle synthesis from turbulent flames and spray flames. The models proposed and applied for the description of the flow-, spray-, combustion- and particle dynamics are formulated for the large eddy simulation methodology. The presented global Simulation approach is independent of the material system and has been used to investigate the synthesis of silica (SiO2) and iron-oxide (Fe2O3) particles from spray flame pyrolysis processes with hexamethyldisiloxane and ironpenthacarbonyl as precursors. An Eulerian-Lagrangian-Eulerian approach has been used to model the gas-, spray- and particle phases respectively. To describe combustion, an existing flamelet generated manifold approach (FGM) combined with the artificially thickened flame method (ATF) was modified to account for (a) spray combustion and (b) to account for spray combustion of three feed Systems - due to the fact that most spray pyrolysis reactors feature such a set-up. Two mixture fractions and one joint reaction progress variable are used as control variables in the combustion model. In contrast to the standard FGM approach, which is based on one Bilger mixture fraction, two element mass fractions are used as control variables to describe the mixture composition. During the flamelet calculations, the chemistry of the precursor was considered in the determination of the thermo-chemical quantities, which were stored in multidimensional look-up tables as functions of the control variables. The general dynamics equation in continuous form, a population Balance equation that describes the evolution of particle from gas phase synthesis, is approximated by (a) a simple monodisperse model, (b) a more advanced bimodal model and (c) a detailed sectional model. While the sectional model considers the formation of particles by nucleation and their growth by coagulation, the monodisperse and bimodal models consider additionally the coalescence of particles. The formation of particles from the gas phase was determined during the flamelet calculations and stored as a nucleation source term in the look-up tables. In the first part of the study, the suitability and validity of the flamelet generated manifold approach combined with the artificially thickened flame method was examined and demonstrated for a well investigated lab-scale spray flame burner operated with ethanol and air. Secondly, the well known monodisperse population balance equation model was applied to study the formation of silica particles from a spray flame pyrolysis reactor operated with ethanol, hexamethyldisiloxane, methane and oxygen. The findings of this study raised the question how well the monodisperse model is suited to describe simultaneously nucleation, coagulation, sintering and mixing as These processes occur simultaneously in turbulent flames. Therefore, the suitability, performance and validity of the three particle models has been demonstrated for a case with simultaneous nucleation, coagulation, coalescence and mixing of particle populations with different histories. Due to the lack of time resolved measurements of particle properties and particle size distributions, a generic test case was used and modified for the aforementioned studies. In the final part of this thesis, the global simulation approach has been used to investigate the formation of silica particles from spray flame pyrolysis in a lab-scale reactor and for the synthesis of iron-oxide particles from a pilot-scale reactor. The simulation results were (a) shown to be in reasonable agreement with the experiments, (b) to help to improve the understanding of the underlying processes and (c) to improve the processes in the investigated reactors.