Classical colloids. Theory of size distribution; paints, coals, greases, etc. Anomalous viscosity in model suspensions

Abstract

An investigation has been made of the conditions in which the stress-strain relationship for stable suspensions of hard, discrete, non-interacting spherical particles in a Newtonian liquid is dependent upon the size distribution of the dispersed phase. Stable suspensions of spherical particles were found t o behave as Newtonian fluids up t o solid concentrations of a t least 20 yo by volume when the dispersed phase possessed a continuous size-distribution curve. In circumstances where effects other than those due t o physical interaction between particles were eliminated , stable suspensions of spherical material composed of varying proportions of two closely-sized fractions, the average diameters of which were widely different, behaved as anomalous fluids a t solid concentrations greater than 7.5 yo by volume over the range of shear rate investigated. At a given rate of shear they behaved similarly t o suspensions of the large spherical particles in a liquid consisting of a suspension of the small particles. This non-Newtonian behaviour cannot at present be satisfactorily explained but i t appears that the aggregate surface area and the degree of packing of the dispersed phase have no influence upon the relative viscosity.

Recent advances on the fundamental physical phenomena behind stability, dynamic motion, thermophysical properties, heat transport, applications, and challenges of nanofluids

“…The colloidal theory states that for sedimentation and aggregation to occur, there is a specified radius below which sedimentation occurs; below that radius, the Brownian diffusion radius balances the gravitational forces acting on the particle changes the characteristic of the nanofluid [136].…”

On the effective viscosity of fresh concrete: A homogenization approach

“…(3) Second scale: Once the viscosity of fresh cement is obtained from the first scale and the volume fraction of gravel particles is given by input data, we can compute the final effective viscosity of fresh concrete using Eqs. ( 6) and (7).…”

“…His theoretical result is limited to suspension containing a very low volume fraction of mono micro size spherical particles of which the interaction between the particles and the effect of c 2019 Vietnam Academy of Science and Technology the transition zone between particles and fluid are negligible. Since Einsteins study, numerous experimental studies followed by empirical formulas have been developed for suspensions at high range of particle volume fraction [4,5], bi-modal and multi-modal particle sizes [6][7][8], divers shape [9][10][11] and nano particles [12][13][14]. Following experimental studies, theoretical concepts are also largely developed to deal with the effective viscosity of suspensions.…”