CFD-DEM modelling of the migration of fines in suspension flow through a solid packed bed

Abstract

In this work, based on the unresolved CFD-DEM framework, a smoothed volume distribution model (SVDM) is developed to simulate the migration of fines in suspension flow through a solid packed bed. In this model, the porosity of coarse solids is calculated by a smoothed particle volume distribution. The model is validated using two solid-liquid systems. Compared with divided particle volume method (DPVM) with a low-resolution mesh, the SVDM method allows a high-resolution mesh and can achieve a high efficiency and applicability. Moreover, the effects of inlet fine concentration and solid/fine size ratio on fines migration behaviour are studied. The results indicate that more holdup of fine powders especially in the upper zone can be captured, when a higher concentration fine phase or a larger size ratio is used. Based on the local holdup information, four powder migration mechanisms are proposed, i.e., size exclusion, powder bridging, powder deposition and powder locking.