One of the solutions to reduce pollutants and increase engine power is to use water spray in internal combustion engines. In this type of engine, fuel and water sprays play an important role in engine performance. In this regard, the purpose of this study is to accurately simulate fuel and water sprays and provide optimal coefficients to achieve the best simulation results. For this purpose, the key features of the spray were first determined for both fuel and water through an experimental work involving high-speed camera photography for the spray in a glass chamber and then using image processing. Next, the three-dimensional simulation of both fuel and water sprays in CONVERGE CFD software was performed completely with the help of suitable physical models to determine the behavior of the spray. Sensitivity analysis and simulation results indicate that the most important effect on the spray behavior in simulation is related to the break-up model. Results also show that water spray has a very solid sstructure so did not show significant change on its behavior by change of injection parameters or model constants. Finally, after accurately identifying the factors affecting the simulation and their effectiveness along with the help of the experimental results, the best coefficients of existing models for accurate simulation of low-pressure fuel and water spray used in IC engines were introduced.