A three-dimensional model for the combustion process in direct-injection diesel engines was established based on submodels for combustion and spray processes. The combustion submodel takes turbulent mixing into account to allow a description of the formation of a premixed combustible mixture, which undergoes an irreversible singlestep chemical reaction. The spray submodel uses the momentum theory, in which the spray is represented by a distributed sink and a source, to simulate gas entrainment and jet penetration, respectively. The ordinary two-equation model is employed as the turbulence model, and other factors are included in accordance with an existing multidimensional approach. Computations carried out for several different conditions in a high-swirl, deep-bowl diesel engine show a reasonable degree of reproduction of the entire combustion process. The combustion-induced flows and their effect on the flowfield are discussed in detail.