The spray tip penetration of diesel sprays was simulated over wide ranges of ambient gas densities using a uniform profile gas jet model equation, which uses the concept of an effective injection velocity. The spray tip penetration obtained with this correlation equation shows a nearly complete match with available experimental data over the range of ambient gas densities from 3.6 to 124 kg/m(3). The spray penetration over this wide range of ambient gas densities was also simulated using the KIVA code, which was implemented with various gas jet submodels, including uniform profile and normal or Gaussian gas jet profile models. The effects of the model's gas entrainment coefficient K and breakup length coefficient C-b on the spray penetration were investigated by parametric studies. Improved predictions of the spray tip penetration where obtained using the Normal Gas Jet Profile model with an entrainment coefficient K = 0.7, in agreement with previous research. An optimal breakup length coefficient C-b = 1.9 was also found when the model includes both the ambient gas density and the spray cone angle as parameters.