Theory of fluctuations in colloidal suspensions undergoing steady shear flow

“…Both g(r) and its Fourier transform S(k) were found to be qualitatively similar to those from the Lionberger-Russel theory, substantially underestimating the magnitude of the distortion from equilibrium when compared to Brownian dynamics simulation. [175], Brady (red), Lionberger-Russel (blue) [190], Ronis (green) [195]. The inset shows the results of the Szamel theory compared with Brownian dynamics simulation data (circles).…”

Section: Alternative Approachesmentioning

confidence: 99%

Nonlinear rheology of colloidal dispersions

Brader¹

2010

J. Phys.: Condens. Matter

128

156

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Colloidal dispersions are commonly encountered in everyday life and represent an important class of complex fluid. Of particular significance for many commercial products and industrial processes is the ability to control and manipulate the macroscopic flow response of a dispersion by tuning the microscopic interactions between the constituents. An important step towards attaining this goal is the development of robust theoretical methods for predicting from first-principles the rheology and nonequilibrium microstructure of well defined model systems subject to external flow. In this review we give an overview of some promising theoretical approaches and the phenomena they seek to describe, focusing, for simplicity, on systems for which the colloidal particles interact via strongly repulsive, spherically symmetric interactions. In presenting the various theories, we will consider first low volume fraction systems, for which a number of exact results may be derived, before moving on to consider the intermediate and high volume fraction states which present both the most interesting physics and the most demanding technical challenges. In the high volume fraction regime particular emphasis will be given to the rheology of dynamically arrested states.

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“…One can therefore resort to either experimental work on the shear-viscosity of hard spheres and/or experimental and theoretical work on the distortion of the pair-correlation function of hard spheres (see, for example, Refs. [50][51][52][53][54].…”

Section: High Shear-rate Responsementioning

confidence: 99%

Constitutive equations for the flow behavior of entangled polymeric systems: Application to star polymers

Briels¹,

Vlassopoulos²,

Kang³

et al. 2011

The Journal of Chemical Physics

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A semimicroscopic derivation is presented of equations of motion for the density and the flow velocity of concentrated systems of entangled polymers. The essential ingredient is the transient force that results from perturbations of overlapping polymers due to flow. A Smoluchowski equation is derived that includes these transient forces. From this, an equation of motion for the polymer number density is obtained, in which body forces couple the evolution of the polymer density to the local velocity field. Using a semimicroscopic Ansatz for the dynamics of the number of entanglements between overlapping polymers, and for the perturbations of the pair-correlation function due to flow, body forces are calculated for nonuniform systems where the density as well as the shear rate varies with position. Explicit expressions are derived for the shear viscosity and normal forces, as well as for nonlocal contributions to the body force, such as the shear-curvature viscosity. A contribution to the equation of motion for the density is found that describes mass transport due to spatial variation of the shear rate. The two coupled equations of motion for the density and flow velocity predict flow instabilities that will be discussed in more detail in a forthcoming publication.

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Theory of fluctuations in colloidal suspensions undergoing steady shear flow

Cited by 74 publications

References 53 publications

Large-Scale Bundle Ordering in Sterically Stabilized Latices

Large-Scale Bundle Ordering in Sterically Stabilized Latices

Nonlinear rheology of colloidal dispersions

Constitutive equations for the flow behavior of entangled polymeric systems: Application to star polymers

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