Earlier experimental studies revealed that, depending on the feeding and discharging conditions, three distinct flow regimes can evolve during the gravity flow of particles through a vertical tube containing static mixer element. In this paper, the results obtained by discrete particle simulation (DPS) are reported. Applying this simulation method for gravity flow, the main characteristics of the flow regimes observed experimentally could be reproduced and explained theoretically. Some important features of gas-solids two-phase flows in tubes containing static mixer element were also revealed. By excavating a great amount of information from the data obtained by DPS, useful data and correlations become available, which are not directly measurable by experiments. Thus, DPS method can help to get useful explanations on particle level for the experimental observations.