An Eulerian-Lagrangian spray and atomization (ELSA) model for high-pressure diesel sprays has been developed in this study. The new model is based on the assumption that the high-pressure diesel spray and atomization process can be described by considering a single effective phase of liquid-gas mixture to represent the turbulent mixing of a liquid jet with ambient gases. A switch from the Eulerian approach to the Lagrangian approach is made beyond the dense spray region near the nozzle. It has long been recognized that the standard k - epsilon turbulence model underpredicts the penetration and overpredicts the spreading rate of high-speed free jets. To correct for these effects, several previously proposed techniques are used to correct for vortex stretching and compressibility effects in high-speed free jets in this study. The turbulence model modifications were applied to high-speed gas and liquid jets, and incorporated into the ELSA model to simulate the high-speed diesel spray and atomization process.