Numerical Study of the Movement of Single Fine Particles in Porous Media Based on LBM-DEM

The fine particle liquid–solid flow in porous media is involved in many industrial processes such as oil exploitation, geothermal reinjection and particle filtration. Understanding the migration characteristics of single fine particles in liquid–solid flow in porous media can provide micro-detailed explanations for the fine particle liquid–solid flow in porous media. In this paper, an existing lattice Boltzmann method–discrete element method (LBM-DEM) is improved by introducing a new boundary thickening direct forcing (BTDF) immersed boundary method (IBM) to replace the classical IBM. The new method is used to investigate the migrations of one, two or three fine particles in a flow field in porous media and the reactions of one, two or three fine particles on the flow field. It is found that the movement distance of a fine particle in porous media does not show a linear correlation with the fine particle’s density. A fine particle with a higher density may move a shorter distance and then stagnates. Although a fine particle with a smaller diameter has a better following performance in a flow field, it is also likely to be stranded in a low-infiltration area in porous media. Under the same increase ratio, the increase in the diameter of a fine particle causes an increased pressure drop of the liquid–solid flow. In some cases, the increase in the quantity of fine particles can intensify the disturbance of fine particles on the flow field, improving the movement of fine particles.