A study was performed to investigate the interesting observation that when using an Eulerian–Eulerian model to simulate a bubble column flow in two dimensions, accuracy did not always increase with increasing grid resolution. A correlation was found between the characteristic bubble diameter numerically specified and grid size, which identified a threshold where results lose physical meaning. An ideal relationship between grid size and bubble diameter was determined to optimize grid resolution and retain accuracy. The two-dimensional (2D) Eulerian model was validated using the experimental data of Rampure et al. (2003, “Modelling of Gas-Liquid/Gas-Liquid-Solid Flows in Bubble Columns: Experiments and CFD Simulations,” Can. J. Chem. Eng., 81 (3–4), pp. 692–706). Further studies demonstrated that grid resolution could be increased to improve the numerical accuracy for three-dimensional (3D) simulations of the bubble column. The novel contributions of this study will show that the ratio of bubble diameter-to-grid cell size should equal 1 / 2 for the 2D simulations.