A computational fluid dynamics-based method proposed in our previous study was used to investigate the effects of flow on the yield in a reactor. First, selectivities in a plug flow reactor and a continuous stirred reactor were calculated to confirm that the proposed method can calculate reactions in ideal flows. The predictions agreed well with exact solutions. Next, three columns with the same volume were used to evaluate selectivity in a consecutive reaction. In addition, marker particles were used to evaluate the mixing behavior. The effects of column geometry on the relation between selectivity of product and conversion of reactant were then discussed. The predictions indicated that selectivity is affected by locations of gas spargers, the direction of liquid injection, and the presence of baffle plates. It was also demonstrated that the proposed method can evaluate the effects of column geometries on flow patterns and reactions.