Abstract:Traditional CFD-DEM model for solid-liquid two-phase flow usually ignored some minor forces and complex particle-turbulence interaction, which led to the insufficient computational accuracy and failure to capture certain important phenomena. A fully coupled CFD-DEM model considering the Loth lift force, virtual mass force, pressure gradient force and turbulence modulation was established to overcome these problems for solidliquid two-phase flow. This fully coupled CFD-DEM model well predicted the particle distribution, two-phase velocity and turbulent kinetic energy in the pipe and can be used for the numerical study of solid-liquid two-phase flow. This model was used to analyze the effects of particle volume fraction at the pipe inlet, conveying speed and particle diameter on the characteristics of solid-liquid two-phase flow in the vertical pipe. The results showed that the lift force drove the particles towards the center of the pipe, and the distribution of particles predicted by the Loth lift force was more consistent with the experiment than that of the traditional Saffman and Magnus lift force. With the increase of the particle volume fraction at the pipe inlet, the axial velocity of each phase was decreased obviously in the pipe, and the effect of turbulence modulation from particles on turbulence led to the decrease of the fluid root mean square (RMS) velocity. With the increase of conveying speed, particles gathered more in the center of the pipe, and the RMS velocity of the fluid was increased rapidly. With the increase of particle diameter, the distribution of particles in the pipe was more uneven, but the effect on the RMS velocity of fluid was very small. The pressure drop was increased gradually with the increase of the particle volume fraction at the pipe inlet, and increased sharply with the increase of conveying speed. Coarse particle diameter had little effect on the pressure drop.