Collective dynamics of flowing colloids during pore clogging

Abstract

Based on direct numerical simulations of the coupled motion of particles and fluid, this study analyzes the collective hydrodynamic and colloidal effects of flowing microparticles during the formation of different 3D clogging patterns at a pore entrance. Simulations of flowing suspensions through a pore with various simulation conditions show that particle concentration and surface interactions play a major role in the occurrence of the bridging phenomenon (simultaneous adhesion of many particles). In the absence of DLVO repulsive forces, plugging is characterized by the temporal reduction of the bulk permeability when increasing the volume fraction of the flowing suspension up to 20%. Under these conditions, different structures of particle aggregates (from cluster to cake plug) are formed at the pore entrance yielding different evolution rates of hydrodynamic resistance to the flow. Taking into account DLVO repulsive forces in simulations for a particle concentration equal to 10%, we observe the transition from dendritic structures (for low repulsion) to dense aggregates (for high repulsion). At high DLVO repulsive forces, the scenario of pore clogging is controlled by the collective behavior of many interacting particles. It leads to the formation of a jamming phase (Wigner glass phase) with transient clusters of interacting particles at the pore entrance. The network of jammed particles collapses when the force chains among the particles are overcome by the flow stress. The build-up and the collapse of the jammed phase at the pore entrance induce temporal permeability fluctuations. According to the relative magnitude of particle-particle and particle-wall interactions, when the jammed phase is disorganized by the flow, the residual force in the network can accelerate particles and lead to particle adhesion at the wall inducing a pore blockage and a rapid reduction of the bulk permeability.

Colloid-interface interactions initiate osmotic flow dynamics

“…4) is brought by the fluid pressure gradient (second term) and by the colloid membrane interaction. The colloid membrane interactions play here the role of a forcing term on the momentum equations of the fluid flow, similarly to a Force Coupling Method [19]. This mathematical writing therefore enables accounting for the interactions between the different phases as schematized in Fig.…”

Dip-coating of suspensions

“…[20] Hence, suspensions and particle-laden flows have led to numerous studies to describe suspension rheology, [25,26,27] inertial suspension flow in pipes, [28,29,30,31] shear-induced migration of particles, [32,33,34] imbibition of suspension, [35] or the clogging in confined flows. [36,37,38,39,40] However, most of these studies have considered bulk flows of suspension, that are well described by constitutive rheological measurements. [26,27] Yet, this approach cannot capture the complexity of the suspension entrainment observed during a dip coating process.…”

Growth of clogs in parallel microchannels

“…Bridging of particles is unlikely to occur with dilute suspensions of particles and sufficiently wide constriction [26]. However, particles smaller than the constriction, with charged surfaces, are still able to clog the device by successive deposition on the walls [29][30][31][32][33]. Experimentally, Wyss et al [34] have observed that particle-wall interactions can determine the clogging dynamics of parallel microchannels.…”