Further remarks on falling coaxial cylinder with wide shear rate range

1978 ◽  
Vol 17 (3) ◽  
pp. 312-313
Author(s):  
A. Rudin ◽  
C. K. Ober ◽  
K. K. Chee
Keyword(s):  
Shear Rate ◽  
Coaxial Cylinder ◽  
Rate Range

Falling coaxial cylinder viscometer with wide shear rate range

1977 ◽  
Vol 16 (6) ◽  
pp. 635-642 ◽  
Author(s):  
K. K. Chee ◽  
A. Rudin
Keyword(s):  
Shear Rate ◽  
Coaxial Cylinder ◽  
Rate Range ◽  
Cylinder Viscometer

Estimation of Red Cell Deformability Based on Flow Curve of Whole Blood in the Higher Shear Rate Range.

2001 ◽  
Vol 27 (2) ◽  
pp. 228-235
Author(s):  
Shinichi Ookawara ◽  
Akihisa Yano ◽  
Kohei Ogawa ◽  
Koichi Taniguchi
Keyword(s):  
Shear Rate ◽  
Whole Blood ◽  
Flow Curve ◽  
Red Cell ◽  
Cell Deformability ◽  
Red Cell Deformability ◽  
Rate Range

Flow behaviour of low solids fresh cheeses

1993 ◽  
Vol 60 (4) ◽  
pp. 593-601 ◽  
Author(s):  
Jozef Korolczuk
Keyword(s):  
Shear Rate ◽  
Initial Level ◽  
Coaxial Cylinder ◽  
Initial Value ◽  
Exponential Equation ◽  
Final Stress ◽  
Final Yield ◽  
Time Required ◽  
Rate Relation ◽  
Cylinder Viscometer

SummaryA computerized, coaxial cylinder viscometer, controlled by a function synthesizer, was used to study the stress characteristics of acid fresh cheeses containing 7·5–8·5% protein and 0–20% fat in total solids, as a function of shearing time (0–3600 s) and of shear rate (0–4·5 s–1). For a given shear rate the stress diminished with time, following an exponential equation. The hypothetical final stress level (Sf for the shearing time t = ∞) represented about half its initial value (Si). For four cheese samples, the time required for the stress to become equal to Sf + (Sf – Sf)/e was 340–560 s. The stress-shear rate relation indicated shear thinning behaviour. The effect of shearing time showed that the material was thixotropic. The cheeses exhibited plastic flow. The initial and final stress levels were hyperbolic functions of the shear rate. Bingham final yield stress (for t = ∞) was 14–50 Pa. It was 15–25% higher for increasing than for decreasing shear rate. Bingham viscosity (for t = ∞) was between 2 and 6 Pa s. It was 10–20% higher for decreasing shear rate. The initial level of Bingham viscosity was ˜ 30% higher than its final value.

Development of Viscosified Acid-Surfactant Solutions for Oilfield Applications: Rheological Properties

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Lionel Talley Fogang ◽  
Muhammad Shahzad Kamal ◽  
Mohamed Mahmoud
Keyword(s):  
Shear Rate ◽  
Acid Solution ◽  
Rheological Properties ◽  
Calcium Chloride ◽  
Elastic Properties ◽  
Salt Concentration ◽  
Shear Thinning ◽  
Rate Range ◽  
Shear Rates ◽  
Surfactant Solutions

Abstract Viscosified acids are desired in several oilfield applications such as in acid diversion and acid fracturing operations. The study aimed to delineate the rheological properties of a novel amine type surfactant and viscosified acid-surfactant solutions. The steady shear and dynamic rheological properties were evaluated by varying the surfactant, acid, and salt concentration. Such a study is required to gauge the suitability of the viscosifying agent in acid stimulation jobs. The surfactant solutions without acid showed shear-thinning behavior, whereas those with acid showed a Newtonian plateau over a wide shear rate range before undergoing shear thinning. This means that over a wide shear rate range, the acid-surfactant solutions become independent of applied shear. At low shear rates, the viscosity of the surfactant was higher compared with the surfactant-acid solution. However, at high shear rates, the viscosity of the surfactant was lower compared with the viscosity of the surfactant-acid solution. There was an optimal salt concentration that improved the viscosity and elasticity of the acid-surfactant solutions. Thus, the rheology of the surfactant solution can be improved by adding both acid and salt. The elastic properties of acid-surfactant solutions were also better compared with the elastic properties of pure surfactant. The addition of acid improved the elastic properties of the surfactant solutions. Constant viscosity over a range of shear rate is a suitable application for acid fracturing operations in which the acid leak-off will be minimal due to the high viscosity. Also, brines in most of the carbonate formation consist of high loading of calcium chloride which was found to have a positive effect on the viscosity. Increasing the calcium chloride leads to an increase in viscosity, and then subsequently decreases the viscosity. This shows that the acid and salt concentration plays a role in modifying the rheological properties of the surfactant solutions.

Metrological Assessment of the Coefficient of Friction of Various Types of Silica Using the Motor Current During ILD-CMP

2004 ◽  
Vol 816 ◽  
Author(s):  
Harald Jacobsen ◽  
Eric Stachowiak ◽  
Gerfried Zwicker ◽  
Wolfgang Lortz ◽  
Ralph Brandes
Keyword(s):  
Shear Rate ◽  
Film Thickness ◽  
Coefficient Of Friction ◽  
Removal Rate ◽  
Rate Range ◽  
Systematic Assessment ◽  
Parameter Domain ◽  
Motor Current ◽  
First Approximation ◽  
The Coefficient Of Friction

AbstractIn the work presented the coefficient of friction (COF) was firstly determined metrologically by a systematic assessment of motor currents for different products of pressure and velocity (p v). With all seven test slurries it could be shown that the inserted energy ECMP is proportional to the product of pressure and velocity. The COF of the parameter domain considered here does not depend on the inserted energy or the product of p v in a first approximation. For all tested slurries it was demonstrated that, both the COF and the removal rate (RR) behave analogously (low COF→ low RR).Measurements of the viscosity η have shown that η is not a constant in the shear rate range relevant for CMP. Using the obtained viscosity values a mean slurry film thickness in the range of 2,5 -C 6 μm could be calculated.

scholarly journals Influence of concentration on the steady and oscillatory shear behavior of umbu pulp

2008 ◽  
Vol 12 (1) ◽  
pp. 87-90 ◽  
Author(s):  
Edimir A. Pereira ◽  
Edimir M. Brandão ◽  
Soraia V. Borges ◽  
Maria C. A. Maia
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Experimental Work ◽  
Loss Modulus ◽  
Dynamic Test ◽  
Frequency Range ◽  
Rate Range ◽  
Soluble Solid ◽  
Weak Gel ◽  
Dynamic Modules

In this experimental work the rheological behavior of umbu pulp has been studied by shear flow (pseudoplasticity, apparent viscosity) and in oscillatory mode (dynamic modules) in the linear domain of viscoelasticity. The studies were carried out with the use of a controlled stress Rheometer Haake RS 100, at different soluble solid concentrations (10, 15, 20 and 25 °Brix), measured at 30 °C. Tests in steady shear were conducted over a shear rate range of 0.1 - 300 s-1 and oscillatory measurements over a frequency range of 0.01 - 100 Hz. The results indicated that umbu pulp behaves as a non-Newtonian fluid, with pseudoplastic characteristics and yield stress appearance and exhibits tixotropic properties. Rheograms were fitted to the Herschel-Bulkey model. From the dynamic test the umbu pulp showed storage modulus (G') values that were always higher than loss modulus (G"), indicating weak gel-like behavior. Storage and loss modulus increased with increase in the concentration.

scholarly journals Guidelines for checking performance and verifying accuracy of rotational rheometers: viscosity measurements in steady and oscillatory shear (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1945-1968 ◽  
Author(s):  
Martin Laun ◽  
Dietmar Auhl ◽  
Rüdiger Brummer ◽  
Dirk J. Dijkstra ◽  
Claus Gabriel ◽  
...  
Keyword(s):  
Shear Rate ◽  
Complex Viscosity ◽  
Angular Frequency ◽  
Temperature Calibration ◽  
Concentric Cylinder ◽  
Rate Range ◽  
Technical Report ◽  
Linear Viscoelastic ◽  
Reference Samples

Abstract The paper addresses techniques for checking the performance of rotational rheometers with cone–plate, plate–plate, or concentric cylinder geometry. We focus on the determination of the viscosity as a function of the shear rate and of the magnitude of the complex viscosity as a function of the angular frequency. After summarizing the relevant definitions and test modes, we show examples of measurements in the linear viscoelastic range, and applications of the Cox–Merz relationship. Sources of reference fluids with defined viscosities are presented, and their use in tests for verification of accuracy is demonstrated. Relevant issues, predominantly for Newtonian reference liquids, are the exploration of measurement limits, related either to the shear rate range or to reliably accessible viscosity levels. Viscoelastic reference samples are also discussed. Prerequisites for sample preparation and loading are addressed. In particular, we present recommendations based on experience from various laboratories. Finally, we discuss the problem of temperature calibration, presenting techniques that allow the determination of the true sample temperature for a given set temperature of the rheometer. This paper summarizes contributions from various industrial and academic laboratories.

Influence of Cluster Formation: Viscosity of Concentrated Emulsions

2003 ◽  
Vol 13 (5) ◽  
pp. 259-264 ◽  
Author(s):  
G. Kyazze ◽  
V. Starov
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Volume Fraction ◽  
Cluster Formation ◽  
Relative Viscosity ◽  
Skim Milk ◽  
Colloid Interface ◽  
Rate Range ◽  
Concentrated Emulsions ◽  
Fraction Comparison

Abstract Recently a new theory of viscosity of concentrated emulsions dependency on volume fraction of droplets (Starov V, Zhdanov G: J. Colloid Interface Sci, 258, 404 (2003)) has been suggested that relates the viscosity of concentrated emulsions to formation of clusters. Through experiments with milk at different concentrations of fat, cluster formation has been validated using optical microscopy and their properties determined using the mentioned theory. Viscometric studies have shown that within the shear rate range studied, both the packing density of fat droplets inside clusters and the relative viscosity of milk (viscosity over skim milk viscosity) are independent of shear-rate, but vary with volume fraction. Comparison of the experimental data with previous theories that assumed that the particles remained discrete shows wide variation. We attribute the discrepancy to cluster formation.

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