Coupled CFD-DEM modelling of clogging of granular columns by cohesive fines

Abstract

The ubiquitous phenomenon of particle migration and clogging in porous media, particularly when involving cohesive fines necessitates a critical need for in-depth understanding from a microscale perspective. Therefore, this study aims to elucidate the migration and clogging behaviour of polydisperse cohesive fines across a granular medium by using the coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM). Primary governing factors including the relative coarse–fine size ratio and the strength of interparticle cohesive force through the concept of bond number are examined in detail from both macro- and micromechanical perspectives. The results reveal that the presence of interparticle cohesion drastically modifies the migration of fine particles, associating with a notable reduction in the infiltration ratio and an increased likelihood of particle deposition. This study innovatively explores the combined effect of the coarse–fine size ratios and cohesive strength on the migratory behaviour of fines through the infiltration ratio and critical time ratio, whereby clogging carries substantial implications on the geo-hydraulic performance of the granular medium. Moreover, in the context of cohesive fines, the Authors propose a comprehensive and novel algorithm for detecting and analysing cohesion-induced agglomeration effect. The results reveal that the formation and breakage of agglomerates due to the metastability of cohesive bonds between fines can be captured to explain the unstable flows occurring through the clogged zones.