Understanding the detailed spray characteristics of a fuel spray undergoing vaporization is a key for better liquid fuel combustion efficiency.The physical processes involved in spray atomization under common conditions for diesel engines are complex and not yet completely understood.In order to understand these processes,researchers have measured various quantities characterizing diesel sprays.Based on these studies,numerical models have been proposed that cover various aspects of these processes.One such aspect is the primary atomization or initiation of droplets from a liquid jet.Among the numerical models proposed,the Surface density-mass fraction(Σ-Y)model has gained popularity for its simplicity and robustness.In the present work,a full Eulerian spray model for high-pressure diesel sprays has been implemented in the general purpose Computational Fluid Dynamics(CFD)solver,ANSYS FLUENT 16.0 via User Defined Functions(UDFs).The 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.The current formulation of Σ-Y is inspired by the Σ-Y model of Vallet et al.(2001)[1] but closely resembles the Ω-Y model suggested by Burluka et al.(2007)[15] and Lebas et al.(2009)[10].The model takes into account the effects of collision,secondary break-up and vaporization on the interface area density,normalized by mixture density,Ω.This numerical model is validated against the experimental measurements for an injector mounted at the optically accessible pressure chamber of WSA,RWTH Aachen,published by Staudt and Pawlowski(2004)[19].Spray penetration and spray characteristics resulting from the simulations compare well with experimental measurements.