Studies to elucidate the mechanism of liquid film flow have been carried out for many years, but the results are still inadequate. Because of random packing, several problems frequently appear in the near-wall region. Therefore, in this study, the liquid film thickness and its spreading behavior were fully investigated using FLUENT v17.1, to unveil the mechanism of the trickle flow, including wall effects. As a quantification, the coefficient of variation (COV) was used to represent the degree of liquid film equilibrium. The results show that trickle flow on the sphere can be roughly separated into three flow stages in which the features of the films are nearly identical. The wall effect, which plays a key role in the poor distribution of the films, is only available if the interstice is lesser than liquid film thickness. To alleviate wall effects, an intermediate velocity of surrounding gas flow is required. (C) 2020 Elsevier B.V. All rights reserved.