Effect of a wall on flow with dense particles

The behavior of dense gas–solid flows in engineering applications such as fluidized beds and pneumatic conveyers is highly complex and a reliable numerical model is required. Such flows are usually within solid walls that considerably affect the flow fields, and it is important to correctly include this effect in numerical models to improve their prediction capability. The observation of microscopic flows near walls can enhance our understanding of the flow behavior and assist in improving models. In this study, direct simulations are performed to investigate the effect of a wall on flow fields at a microscopic level. The effects of the bulk void fraction, particle Reynolds number, and particle diameter are investigated. The prediction performances of existing correlation equations usually used in mesoscopic model calculations are also investigated. It is found that the Ergun and Beetstra equations produce large discrepancies in the region within a distance equal to the particle diameter from the wall.