Metal powder production by gas atomization is widespread due to the powder morphology and high production yield for additive manufacturing and powder metallurgy processes. Increasing the process efficiency through nozzle geometry optimization is essential for sustainability. Computational Fluid Dynamics (CFD) can be used to optimize the nozzle geometry by controlling the fluid flow more efficiently. The Reynolds Stress Model (RSM) was used in this study to model a single-flow CFD simulation in a gas atomizer. CFD simulations were conducted to estimate the behavior of atomizing gas flow. The RSM results for gas flow behavior are compared with the real-gas flow data from gas-atomizing nozzle experiments. The experimental melt tip base pressure was found to be only 1.5-4.2% lower than the values predicted by the RSM solution, and no flow separation was observed during the metal powder production. The findings of this investigation demonstrate that the Reynolds Stress Model effectively predicts gas flow patterns beneath the melt tip base and along the nozzle's external surface. The RSM turbulence model can be employed to formulate design principles and operational guidelines for advanced, high-efficiency atomization nozzles, as well as to optimize current nozzle geometries.