Clogging effect of fines in seepage erosion by using CFD–DEM

Abstract

The macroscopic phenomena and microscopic origin of penetrative migration and retention of fine particles in porous skeleton under the action of seepage are not yet clear. Migrating fine particles experience physical interactions with impermeable walls, carrier fluids, particle skeleton and other fines. Therefore, the simulations of suffusion based on the coupled computational fluid dynamics–discrete element method (CFD–DEM) are carried out with consideration of different coarse particle size distributions, flow velocities and inflow fines concentrations. Simulations are performed by releasing continuously produced fines into the coarse-grained matrix under hydraulic force. Macroscopic alterations (including the loss rate, concentration ratio, concentration region of cluster, velocity and size distribution of fine particle, pore throat diameter and permeability) and microscopic features (including interparticle force network, the spatial distribution and velocity field of fines) are quantified during suffusion. The results reveal that the pore size of porous media significantly contributes to the degree and position of clogging. Flow velocity affects interception efficiency and distribution of clusters. Additionally, the prominent development of particle clusters in the flow-avoidable areas is aided by the appearance of more inflow fines. With both macroscopic and microscopic responses, this study may increase the knowledge of clogging phenomena during suffusion.