Drag coefficient of a spherical particle attached on the flat surface

The previous analytical solution for the drag coefficient (C _d) for a spherical particle attached on the flat surface, which was derived by O'Neill (1968), is only valid in the creeping flow conditions. It is important to extend O'Neill's formula to cover a wide range of particle Reynolds number (Re _p). In this study, the drag coefficient was calculated numerically to cover Rep from 0.1 to 250. For a particle suspended in the air, an empirical drag coefficient exists, which is defined as C _d = f × 24/Re _p, where f is a correction factor depending on Re _p. The applicability of the correction factor f for O'Neill's analytical equation for the spherical particle attached on the flat surface for Re _p = 0.1 to 250 was examined in this study.