CFD-DEM simulation of the pneumatic conveying of fine particles through a horizontal slit

Fine particles play a significant role in many industrial processes.To study the dynamic behavior of fine particle and their deposition in rock fractures,the pneumatic conveying of fine particles(approximately100 μm in diameter) through a small-scale horizontal slit(0.41 m × 0.025 m) was studied,which is useful for the sealing technology of underground gas drainage in coal mining production.The CFD-DEM method was adopted to model the gas-particle two-phase flow;the gas phase was treated as a continuum and modeled using computational fluid dynamics(CFD),particle motion and collisions were simulated using the DEM code.Then,the bulk movement of fine particles through a small-scale horizontal slit was explored numerically,and the flow patterns were further investigated by visual inspection.The simulation results indicated that stratified flow or dune flow can be observed at low gas velocities.For intermediate gas velocities,the flow patterns showed pulsation phenomena,and dune flow reappeared in the tail section.Moreover,periodic flow regimes with alternating thick and sparse stream structures were observed at a high gas velocity.The simulation results of the bulk movement of fine particles were in good agreement with the experimental findings,which were obtained by video-imaging experiments.Furthermore,the calculated pressure drop versus gas velocity profile was investigated and compared with relative experimental findings,and the results showed good agreement.Furthermore,the particle velocity vectors and voidage distribution were numerically simulated.Selected stimulation results are presented and provide a reference for the further study of fine particles.