In recent times, combustion modelling employing computational fluid dynamics (CFD) in combination with experiment has become an irreplaceable tool in the design process of the diesel engines. Combustion process as a phenomenon of exceptional complexity can be numerically solved with detailed chemical kinetics or with the utilisation of approximated combustion models. Detailed chemical kinetics provides a comprehensive insight into the chemical aspect of the combustion process, while combustion models are described with approximated chemical kinetics in order to reduce the computational demand. An appropriate modelling approach to overcome these challenges is the Flamelet generated manifold (FGM) combustion modelling approach, which computes the chemistry kinetics in preprocessing and stores the result data in a look-up table that is interpolated during the CFD simulations. One of the combustion models, which has proven an ability to simulate the combustion process in internal combustion engines is Three-zones extended coherent flame model (ECFM-3Z+). In this thesis, ECFM-3Z+ and FGM approaches were employed for the calculation of combustion process in a diesel engine. The primary aim of the thesis is to analyse and validate numerical results obtained with FGM and ECFM-3Z+ models against experimental data. Numerical simulations are performed using commercial CFD software AVL FIRE TM, where the calculated results such as mean in-cylinder pressure, mean temperature, rate of heat release and NO emissions are calculated for single and multi-injection strategies. The NO emission trend observed in the experiment is well reproduced with both combustion models, while the computational time for CFD simulations with FGM is reduced by half. The results obtained with both combustion modelling approaches are found to be in a good agreement with the experimental data. Thus it is conducted, that both ECFM-3Z+ and FGM combustion modelling approaches are capable of predicting the combustion process in the real industrial diesel engines.