Viscosity Function for Yield-Stress Liquids

Abstract

A viscosity function for highly-shear-thinning or yield-stress liquids such as pastes and slurries is proposed. This function is continuous and presents a low shear-rate viscosity plateau, followed by a sharp viscosity drop at a threshold shear stress value (yield stress), and a subsequent power-law region. The equation was fitted to data for Carbopol aqueous solutions at two different concentrations, a drilling fluid, an water/oil emulsion, a commercial mayonnaise, and a paper coating formulation. The quality of the fittings was generally good.

Modeling the thixotropic behavior of structured fluids

“…(23) is a modified version of the one proposed by de Souza Mendes and Dutra [10] for Hershel-Bulkley-like materials. It is able of predicting all the features observed in steady-state data for viscoplastic materials.…”

Experimental studies of multi-layer flows using a visco-plastic lubricant

“…There are many ways to determine the yield stress of such fluids, see, e.g. [17]. In our experiments the yield stress values of the Carbopol solutions were determined using a combination of three methods: inspection of the flow curve at low shear, maximal instantaneous viscosity technique, and a creep test.…”

Analysing the large amplitude oscillatory shear of the Cross and Cross–Maxwell models with the aid of Fourier transform rheology using the example of a solvent-borne alkyd primer

“…It is clear from equations (30) and (34) that K 1 is the material parameter which influences the transition between the two Newtonian-like regions ( [46], [47]) if η 0 and η ∞ are fixed. Furthermore, κ 2 is not entirely free of restrictions in order to ensureγ…”