Rheological behavior of colloidal suspension with long-range interactions

Abstract

In this work, we study the constitutive behavior of interacting colloidal suspensions for moderate and high concentrations. Specifically, using a lattice Boltzmann solver, we numerically examine suspensions flowing through narrow channels, and explore the significance of the interaction potential strength on the system's macroscopic response. When only a short-range interaction potential is considered, a Newtonian behavior is always recovered and the system's effective viscosity mostly depends on the suspension concentration. However, when using a Lennard-Jones potential we identify two rheological responses depending on the interaction strength, the volume fraction, and the pressure drop. Exploiting a model proposed in the literature we rationalize the simulation data and propose scaling relations to identify the relevant energy scales involved in these transport processes. Moreover, we find that the spatial distribution of colloids in layers parallel to the flow direction does not correlate with changes in the system macroscopic response; but, interestingly, the rheology changes do correlate with the spatial distribution of colloids within individual layers. Namely, suspensions characterized by a Newtonian response display a cubiclike structure of the colloids within individual layers, whereas for suspensions with non-Newtonian response colloids organize in a hexagonal structure.

Polymer-functionalized polymer nanoparticles and their behaviour in suspensions

“…10 In comparison with solutions of linear polymer chains, the overlap concentration of solutions of dendrimers or of solutions of polymers having a branched architecture occurs at higher concentrations because of the limited effective chain entanglement. 11 In comparison with polymer solutions, the rheological behaviour of colloidal dispersions is controlled by even more factors; the viscoelasticity not only depends on the volume fraction occupied by the colloids and the colloid-colloid interaction, 12 but is also affected by the reorganization and reorientation of the particles in suspension and their effects on the local flow patterns, 13,14 and the formation (or destruction) of colloidal mesostructures. 15,16 Furthermore, when dealing with soft and deformable colloids in suspension, both the shape and the volume occupied by the particles can change under the application of shear, leading to strong flow-dependent behaviour.…”

Numerical simulation method for Brownian particles dispersed in incompressible fluids

“…Examples include processes of producing secondary-battery electrodes and coats of paint [1,2]. Recently, functional fluids that change their rheological properties have also attracted attentions [3,4]. The particles suspended in solutions in those systems thermally fluctuate, which is referred to as the Brownian motion.…”