In a single wafer processing, it is crucial to predict and control liquid film flow flowing over the rotating disk and the chemical solution concentration distribution to achieve efficient cleaning. This study numerically obtained the distribution of liquid film and cleaning solution concentration on a rotating disk using the open-source program, OpenFOAM. We prevented numerical diffusion from liquid to gas by incorporating a conservative scheme into the mass transport equation. The obtained liquid film distribution and surface etching amount agreed with the literature.