A study on the modeling of fuel sprays in diesel engines will be presented. First, modeling of non-reacting diesel spray formation is studied in Fluent and Star-CD. The main objective however is to model combustion of the spray using a generic approach. This is achieved by applying a detailed chemistry tabulation method, called FGM (Flamelet Generated Manifold). Using this approach will make additional ignition modeling, which is conventional, obsolete. The FGM method is implemented in Fluent and Star-CD. Subsequently, constant volume spray combustion and full engine cycle simulations are performed.Spray formation is modeled with Lagrangian type models that are available in Fluent and Star-CD, and also with a 1D Euler-Euler spray model that is implemented and applied in 3D Fluent simulations. The results are compared with EHPC (Eindhoven High Pressure Cell) experiments, data from Sandia National Laboratories and IFP (Institut Français du Pétrole). The newly created combination of the 1D spray model with 3D Fluent is able to predict spray lengths and shapes quantitatively well. It also offers the advantage of a proper mesh resolution behavior (higher resolution gives better solutions), and is suitable for parallel computing.Combustion of the fuel spray is modeled with a tabulated chemistry approach (FGM). The manifold is created with igniting diffusion flame solutions. Important characteristics like auto-ignition and flame lift-off are captured without applying an explicit ignition model, showing the generic nature and therefore the potential of the applied method. Results with heptane as a surrogate for diesel fuel compare well with experimental observations. Also the first full engine cycle simulations for a heavy-duty diesel engine show promising results.