Obtaining the Shear Stress versus Shear Rate Relationship and Yield Stress of Blood from Capillary Viscometry Data by Tikhonov Regularization

2002 ◽  
Vol 18 (4) ◽  
pp. 879-884 ◽  
Author(s):  
Y.L. Yeow ◽  
Y.-K. Leong ◽  
S.R. Wickramasinghe ◽  
B. Han
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Tikhonov Regularization ◽  
Rate Relationship

Rheology and structure of blood suspensions

1964 ◽  
Vol 19 (1) ◽  
pp. 127-133 ◽  
Author(s):  
S. E. Charm ◽  
W. McComis ◽  
G. Kurland
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Structural Model ◽  
Cell Suspensions ◽  
Rate Curve ◽  
Red Cell ◽  
Shear Rates ◽  
Straight Line ◽  
Rate Plot

A structural model developed for kaolin suspensions was applied to blood in order to determine the structure and strength of the red cell suspensions. The yield stress of red cell suspensions determined in settling experiments agreed with the yield stress determined from shear stress-shear rate information employing Casson's equation. Theoretical considerations indicate that the shear stress-shear rate curve for blood should approach a straight line. This was found to be true at shear rates above 40 sec-1. The slope of this line was predicted from calculations based on sedimentation experiments and a modified Einstein's equation. The data suggest that the curvature of the shear stress-shear rate plot at low shear rates is due to aggregates of cells which break down under increasing shear rate, resulting finally in individual flocs. It is suggested that a floc consists of one to four cells with adhering plasma. The aggregate was calculated to have twice as much plasma associated with it as does a floc. However, the size of the aggregate could not be determined since the number of flocs associated with an aggregate could not be determined. shear stress-shear rate curve; red cell floc; red cell aggregate; sedimentation rate; blood viscosity and flow Submitted on February 28, 1963

Yield Stress of Emulsions and Suspensions as Measured in Steady Shearing and in Oscillations

2008 ◽  
Vol 18 (4) ◽  
pp. 44790-1-44790-8 ◽  
Author(s):  
I. Masalova ◽  
A.Ya. Malkin ◽  
R. Foudazi
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Flow Curves ◽  
Dynamic Yield Stress ◽  
Shear Rates ◽  
Meaningful Material ◽  
Dynamic Yield ◽  
Steady Shearing ◽  
Concentrated Emulsions

Abstract The yield stresses of five samples (two highly concentrated emulsions, two Kaolin dispersions and mayonnaise) were determined in two ways. In one case, steady shear experiments were performed over a range of incrementally decreasing shear rates. The resulting flow curves, plotted as shear stress against shear rate, clearly showed the existence of a yield stress for each sample, the Herschel-Bulkley model being fitted to obtain values. In the second case, oscillatory amplitude sweeps were performed at three frequencies, and the “dynamic yield stress” was defined as the stress at which deviation from linearity occurred; this procedure has often been used to determine the yield stress of emulsions. It was found that the dynamic yield stress is frequency dependent, and cannot therefore be thought of as physically meaningful material property. At no frequency did the dynamic yield stress correlate with the yield stress obtained from the flow curves.

Calibration of a Commercial Kneader for Rheological Applications

2002 ◽  
Vol 12 (5) ◽  
pp. 241-251
Author(s):  
Tim Kealy ◽  
Carlos Tiu
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Data Interpretation ◽  
Viscous Fluids ◽  
High Yield ◽  
Shear Rates ◽  
Tube Type ◽  
High Torque ◽  
High Plastic

Abstract In the case of some highly viscous fluids, or thick pastes (such as those exhibiting high yield stress and/or high plastic viscosity), neither rotational nor tube type viscometers are suitable for rheological characterisation. Due to their capacity for generating and maintaining high torque or high rates of rotation, kneaders and mixers can often engender shear rates in excess of those of conventional rotational viscometers. Often these devices are instrumented, to measure and record the rate of rotation of the mixing blades and the related torque on the shaft turning the blades. The major problem facing users of these mixers lies in data interpretation, specifically in relating rate of rotation and torque data to shear rate and shear stress respectively. If it were possible to obtain such relationships, useful rheological data could be generated with instrumented mixers.

Nondimensional Analysis of Electrorheological and Magnetorheological Dampers Using a Herschel-Bulkley Constitutive Model

Aerospace ◽  
2003 ◽  
Author(s):  
Norman M. Wereley
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Constitutive Model ◽  
Yield Stress ◽  
Flow Mode ◽  
Damping Capacity ◽  
Bingham Plastic ◽  
Field Dependent ◽  
Local Shear ◽  
Local Shear Stress

Quasisteady modeling of linear stroke flow mode magnetorheological (MR) and electrorheological (ER) dampers has focused primarily on the utilization of the Bingham-plastic constitutive model to assess performance metrics such as damping capacity. In such Bingham-plastic MR (or ER) flows, the yield stress of the fluid, τy, is activated by applying magnetic (or electric) field. The Bingham-plastic model assumes that the material is in either (1) a preyield condition where the local shear stress is less than the yield stress, τ < τy, or (2) a postyield condition, where the local shear stress is greater than the yield stress, τ > τy, so that the material flows with a constant postyield viscosity. The objective of this paper is to analyze the damping capacity of such a controllable MR or ER damper in the situation when the field dependent fluid exhibits postyield shear thinning or thickening behavior, that is, the postyield viscosity is a function of shear rate. A Herschel-Bulkley model with a field dependent yield stress is proposed, and the impact of shear rate dependent viscosity on damping capacity is assessed. Key analysis results—velocity profile, shear stress profile, and damping coefficient—are presented in a nondimensional formulation that is consistent with prior results for the Bingham-plastic analysis. The nondimensional analysis formulated here clearly establishes the Bingham number as the independent variable for assessing flow mode damper performance.

Viscosity Function for Yield-Stress Liquids

2004 ◽  
Vol 14 (6) ◽  
pp. 296-302 ◽  
Author(s):  
Paulo R. Souza Mendes ◽  
Eduardo S. S. Dutra
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Power Law ◽  
Drilling Fluid ◽  
Oil Emulsion ◽  
Viscosity Function ◽  
Coating Formulation ◽  
Low Shear

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.

POLAR-MOLECULE-DOMINATED ELECTRORHEOLOGICAL (PM-ER) FLUIDS: THE PROPERTIES AND EVALUATIONS

2011 ◽  
Vol 25 (07) ◽  
pp. 957-962 ◽  
Author(s):  
KUNQUAN LU ◽  
RONG SHEN ◽  
XUEZHAO WANG ◽  
DE WANG ◽  
GANG SUN
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Linear Dependence ◽  
Polar Molecule ◽  
High Yield ◽  
Electric Response ◽  
New Type ◽  
Er Fluids ◽  
Er Fluid

In recent years, a new type ER fluids named as polar-molecule-dominated electrorheological (PM-ER) fluids have been developed, of which the yield stress can reach more than 100 kPa and behaves a linear dependence on the electric field. A brief description on the composition and synthesizing method for the materials is given. The main merits of PM-ER fluid are as follows: high yield stress, the shear stress increasing with shear rate up to more than 103 s -1, low current density, rapid electric response and anti-sedimentation. Some perspectives on PM-ER fluid and its applications are presented.

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