In the study we analyze the flow fields around an air cleaner using the activated carbon by CFD, because there are many problems in the pre-experiments to make an air cleaner using the activated carton. We apply the physical models and porous zones of the Fluent to the analysis. The porous zones are used when pressure losses are known and the porosity plate analysis method is used when the Ergun equation is used. The porous zone analyses are performed in two and three dimensions and the Ergun equation cannot obtain available values in two dimensions. In the other cases this results show that the porous zone method can be a alternative to the experiment