Size and Structure of Clusters Formed by Shear Induced Coagulation: Modeling by Discrete Element Method

Abstract

The coagulation process has a dramatic impact on the properties of dispersions of colloidal particles including the change of optical, rheological, as well as texture properties. We model the behavior of a colloidal dispersion with moderate particle volume fraction, that is, 5 wt %, subjected to high shear rates employing the time-dependent Discrete Element Method (DEM) in three spatial dimensions. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to model noncontact interparticle interactions, while contact mechanics was described by the Johnson-Kendall-Roberts (JKR) theory of adhesion. The obtained results demonstrate that the steady-state size of the produced clusters is a strong function of the applied shear rate, primary particle size, and the surface energy of the particles. Furthermore, it was found that the cluster size is determined by the maximum adhesion force between the primary particles and not the adhesion energy. This observation is in agreement with several simulation studies and is valid for the case when the particle-particle contact is elastic and no plastic deformation occurs. These results are of major importance, especially for the emulsion polymerization process, during which the fouling of reactors and piping causes significant financial losses.

Numerical investigation of hard-gel microparticle suspension dynamics in microfluidic channels: Aggregation/fragmentation phenomena, and incipient clogging

“…The Johnson-Kendall-Roberts (JKR) [24] model for particle-particle adhesion/collision is employed. A number of works available in the literature have used this contact model for simulating aggregation/fragmentation process of particulate aerosol systems [16,17] and, more recently, cluster formation in shear-induced coagulation in a system made by hard spherical particles in water [25,26]. To the best of our knowledge, however, this is the first time that aggregation/breakage phenomena are studied for a system made by a water suspension of hard-gel particles flowing in a microfluidic device.…”

Aggregation and breakup of acrylic latex particles inside millimetric scale reactors

“…At moderate volume concentration ( = 0.05), Kroupa et al [37] observed discrepancies with Zaccone approach. The authors explain that for this concentration value, not only rupture but also aggregation will have an impact on equilibrium.…”

“…The most important feature of this equation is that the scaling exponent p is directly dependent of the structure of the considered aggregate. This theoretical consideration was subsequently used in other works as a comparison basis with results either obtained by experiments [35] or numerical investigations [36,37].…”

Aggregation and clogging phenomena of rigid microparticles in microfluidics

“… 2016 ), and to identify the cluster generation in shear-induced coagulation of microparticles flowing in water (Kroupa et al. 2014 , 2015 ).…”