This study performed a spray-painting simulation based on the Large Eddy Simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) for spray painting using a rotary atomizer. The LES better reproduced the flow field and spray dispersion between the bell and target than the RANS. Also, the region called “over-spray” in the radially outside of the bell, in which the droplets stay, was formed, and the residence time became longer for droplets with larger diameter regardless of numerical methods for turbulent flow. Further, the transfer efficiency (TE) in the RANS was almost constant, independent of droplet diameter because all the eddy was modeled in the RANS, and the turbulent fluctuation a droplet received near the target was isotropic. In contrast, the TE in the LES varied depending on droplet diameter and showed the maximum value because only small eddies are modeled in the LES, and the turbulent fluctuation was more realistic.
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