CFD-DEM modelling of hydraulic conveying of solid particles in a vertical pipe

This paper presents a numerical study of hydraulic conveying of coarse solid particles by means of the combined approach of Computational Fluid Dynamics (CFD) for the liquid phase and Discrete Element Method (DEM) for particles. Via the model validation, it proves the reasonability of applying the CFD-DEM method in the simulation of this flow system, where the lift force acting on a particle needs to be considered. Numerical results show that particles tend to concentrate in the middle of the vertical pipe. Increasing feed solid concentration and conveying speed gives a more dispersed distribution of particles and leads to an increase of pressure drop. In contrast, particle diameter has a negligible influence on instantaneous flow regimes and pressure drop. Under all the operating conditions considered, time-averaged variables including solid volume fraction, axial liquid velocity, and axial solid velocity all present maximum values in the middle of the pipe, which decline gradually in the radial direction toward the wall. These results are expected to shed light on the optimization of hydraulic conveying.