An Eulerian-Eulerian multiphase solver of the open-source CFD software Open-Foam was used to numerically compute the film cooling investigation on a flat plate with various numbers of deposition. The analysis was performed at different mist loading fractions, droplet diameters and blowing ratios. Various numbers of depositions were configured in the domain at different locations. An increase in the number of depositions at the plate surface raised the turbulence mixing of the fluids. It eventually weakened the film cooling performance. Moreover, the formation of depositions towards upstream after the coolant’s exit hole led to a decreasing film cooling effectiveness. It was also observed that the cooling performance was maximum at the highest blowing ratio, highest loading fraction, lowest droplet diameter and lowest injection angle.