Viscosity Measurements Of Fluids Research Articles

Ultrasonic Measurement of Fluid Viscosity for Blood Characterization

Although plaque rupture in arteriosclerosis is affected by not only its strength but also by hemodynamic factors, such as blood pressure and shear stress, in particular, the viscous coefficient which directly controls the magnitude of shear stress might be a risk factor in plaque rupture. Therefore, if the viscous coefficient can be assessed noninvasively, it can be a useful index for prediction of a plaque rupture and assessment of various diseases. In this work, an ultrasonic methodology to estimate the viscous coefficient was investigated by numerical simulation and flow-phantom experiment as the fundamental investigation for noninvasively assessing the viscous characteristics of blood. These results show that the proposed method is useful for estimating the kinematic viscosity coefficient in the viscous evaluation of blood.

Nuclear magnetic resonance imaging for viscosity measurements of non-Newtonian fluids using a miniaturized RF coil

This work reports on applications of a miniaturized RF coil combined with a capillary tube for the design of a portable on-line/in-line magnetic resonance imaging (MRI) based viscometer. A microfabricated Helmholtz RF coil with the average diameter of 7 mm and a Teflon tube with ID = 1.02 mm were utilized. Tube flows of two aqueous CMC polymer solutions (2% with MW = 250k and 1% with MW = 700k) of different viscosities at 1.99 µL s−1 volumetric flow rate were monitored. It was shown that the RF coil and the capillary permit measurement of shear thinning phenomena during flow. A constitutive power law model was used to analyse the tube flows. Viscosity was successfully measured for both the CMC solutions. The less viscous CMC solution was found to have the power index n = 0.77 ± 0.06 and the flow consistency coefficient K = 1.68, whereas the more viscous CMC solution exhibited n = 0.5 ± 0.03 and K = 7.23. The MRI measurements compared well with measurements of the same samples performed on a conventional rotational rheometer. The range of shear rates covered by the obtained MRI viscosity data was 3–20 s−1.

Measurement of fluid viscosity at microliter volumes using quartz impedance analysis

The purpose of this work was to measure viscosity of fluids at low microliter volumes by means of quartz crystal impedance analysis. To achieve this, a novel setup was designed that allowed for measurement of viscosity at volumes of 8 to 10 microL. The technique was based on the principle of electromechanical coupling of piezoelectric quartz crystals. The arrangement was simple with measurement times ranging from 2 to 3 minutes. The crystal setup assembly did not impose any unwanted initial stress on the unloaded quartz crystal. Quartz crystals of 5- and 10-MHz fundamental frequency were calibrated with glycerol-water mixtures of known density and viscosity prior to viscosity measurements. True frequency shifts, for the purpose of this work, were determined followed by viscosity measurement of aqueous solutions of sucrose, urea, PEG-400, glucose, and ethylene glycol at 25 degrees C +/- 0.5 degrees C. The measured viscosities were found to be reproducible and consistent with the values reported in the literature. Minor inconsistencies in the measured resistance and frequency shifts did not affect the results significantly, and were found to be experimental in origin rather than due to electrode surface roughness. Besides, as expected for a viscoelastic fluid, PEG 8000 solutions, the calculated viscosities were found to be less than the reported values due to frequency dependence of storage and loss modulus components of complex viscosity. From the results, it can be concluded that the present setup can provide accurate assessment of viscosity of Newtonian fluids and also shows potential for analyzing non-Newtonian fluids at low microliter volumes.

원형 봉의 비틀림 진동에 의한 유체 점도 측정 연구

원형 봉의 비틀림 진동에 의한 유체 점도 측정 연구

A method of isolating surface tension and yield stress effects in a U-shaped scanning capillary-tube viscometer using a Casson model

The present study introduces a method to consider different surface tensions at two riser tubes for the viscosity measurements of fluids using a U-shaped scanning capillary-tube viscometer (SCTV). The accuracy and repeatability of the SCTV were demonstrated by comparing the viscosity results of distilled water obtained from the SCTV with the well-accepted reference data for water. Non-Newtonian viscosities of bovine blood containing 7.5% ethylenediaminetetraacetic acid (EDTA) and fresh human blood were measured at 25 °C and at a body temperature of 37 °C, respectively. The viscosity results for bovine blood gave excellent agreement with the results obtained from a rotating viscometer. The results demonstrate that whole blood viscosity can be measured over a range of shear-rates in less than 2–3 min without any anticoagulants using disposable U-shaped capillary-tube sets.

A new mass-detecting capillary viscometer

The mass-detecting technique has been applied to design a capillary viscometer for viscosity measurements of both Newtonian and non-Newtonian fluids over a range of shear rates. Flow-rate and pressure-drop measurements are replaced with a measurement of liquid-mass variation with time. Using a precision balance, one can measure the variation of fluid mass collected in the receptacle, m(t), from which the test fluid viscosity and shear rate are mathematically calculated. The feasibility and accuracy of the mass-detecting technique have been demonstrated for water and non-Newtonian fluids by comparing results against established viscosity measurement techniques. The advantages of this design are simplicity (i.e., ease of operation and no moving parts), low cost, and the ability to measure viscosity over a relatively broad range of shear rates.

A COMPARATIVE STUDY OF THE PERFORMANCE OF SELECTED IN‐LINE VISCOMETERS ON NEWTONIAN AND SHEAR‐THINNING FLUIDS*

Three commercial instruments for in‐line process measurement of fluid viscosity (an oscillating sphere viscometer, a tube viscometer and a coaxial cylinder viscometer) were evaluated using a Newtonian (60% sucrose) and two shear‐thinning fluids (0.5% xanthan gum and 2% hydroxypropyl methylcellu‐lose). The oscillating sphere viscometer required little or no calibration to measure the viscosity of Newtonian fluids. Otherwise, when compared to results given by analytical off‐line rheometry, the in‐line viscometers were found to be grossly inaccurate in predicting viscosity. A methodology is presented to correct the flow curves generated by each in‐line instrument such that the output measurements are consistent with that given by off‐line rheometry. Additional characteristics of each instrument that should be considered when choosing an instrument for in‐line process application are presented.

A scanning dual-capillary-tube viscometer

The present study introduces the concept of a new scanning dual-capillary-tube viscometer (SDCV) for viscosity measurements of both Newtonian and non-Newtonian fluids, including whole blood, over a wide range of shear rates. The flow rate and pressure drop measurements that are usually required for the operation of a capillary-tube viscometer are replaced with two measurements of liquid-height variation with time. Using a charge-coupled device sensor array, one could measure the variation of fluid levels at each riser tube, h1(t) and h2(t), from which the test fluid viscosity was calculated. The feasibility and accuracy of the SDCV technique has been demonstrated for a standard-viscosity oil and for bovine blood by comparing results against established viscosity measurement techniques. A power-law viscosity model was used to correlate the data for the latter. The dual-capillary-tube viscometer extends the shear rate range as low as 0.1 s−1 for both the viscosity of mineral oil (9.9 cP at 25 °C) and bovine blood with 3% ethylenediaminetetraacetic acid at room temperature.

Concentric cylinder end effects and fluid inertia effects in controlled stress rheometry: part I: numerical simulation

In a commercially available CSR controlled stress rheometer, the theoretical formulae for calculating the shear viscosity and complex viscosity of a fluid in a recessed concentric cylinder geometry, do not take into account end effects. The first part of this paper is concerned with a theoretical prediction of end effects on steady shear viscosity measurements of Newtonian fluids in a recessed concentric cylinder geometry. Fluid inertia effects are included in the theory and the relevant equations are solved using a perturbation analysis which is valid for low Reynolds number flows. The perturbation equations are solved numerically using a finite difference method. From this theory, correction formulae are produced to compensate for end effects and second order fluid inertia effects in steady shear flows on a CSR rheometer. End effects are also investigated for shear thinning fluids using the Polyflow package, and results show that they are less significant than those for Newtonian fluids. The second part of this paper is concerned with a theoretical prediction of the end effect of a recessed concentric cylinder geometry on complex viscosity measurements of a generalised linear viscoelastic fluid. The theory will include a first and second order fluid inertia perturbation analysis and the relevant equations are solved using a finite difference method. Using this theory, the existing oscillatory shear formulae which include second order fluid inertia effects, are modified to compensate for end effects.

Measurements of viscosity and permeability of two phase miscible fluid flow in rock cores

This paper describes the application of 1H magnetic resonance imaging (MRI) to the measurement of fluid viscosity and rock core plug permeability during two phase miscible displacements in certain rock types. The core plug permeability was determined by monitoring glycerol solutions displacing D 2O. Simple physical principles were used to calculate the core permeability from the measured displacement angle for a set of Lochaline sandstone core plugs. In a further experiment the viscosity of polyacrylamide solution 1500 ppm was determined in the core plug. The permeability and viscosity results compared well to conventional core analysis methods.

細線加熱法による粘度測定指標値の特性

細線加熱法による粘度測定指標値の特性

Degradation of Phenol by Immobilized Mycelium of Fusarium Flocciferum in Continuous Culture

Continuous phenol degradation was studied in a completely mixed reactor, at steady state conditions, using the mycelium of Fusarium Floociferum immobilized in Polyurethane foam. Experiments at different dilution rates, 0.069, 0.118 and 0.196h−1 with an influent phenol concentration of 1g/l, showed a virtually complete substrate utilization over a period of four months. Low biomass productivity values of suspended cells were found, 0.21, 0.34 and 1.81g d.w./l. day, especially when compared with those obtained with the free cell system at similar conditions: 0.955 and 6.73g d.w./l.day for 0.063 and 0.116h dilution rates. The immobilized cells behaviour at different feed substrate concentrations was studied at D=0.196h.−1 corresponding to a retention time of 5.1h. The results indicate that above 1g/l the complete phenol removal is not achieved. A progressive increase in the outlet concentration was observed, attaining a value of 284mg/l at 1.5g/l. Respiratory experiments made with the immobilized cells taken from the reactor along with these experiment, indicate that the viability is retained by the mycelium, pointing out its ruling part in the phenol degradation. Culture fluid viscosity measurements were made and the rheological characteristics of the two systems were investigated. A non-Newtonian fluid was observed in the free cell system, with a shear-thinning behaviour. The immobilization had a beneficial effect on the rheology of the fluid i.e. the viscosity was much lower,1.2 c.p.s. and there was a tendency to approach Newtonian behaviour.

The use of ammiotic fluid viscosity measurements to establish fetal lung maturity

A Haake viscosimeter was used to determine the viscosity of amniotic fluid and this value correlated with fetal lung maturity. The results were evaluated along the weeks of pregnancy and compared to those obtained using Gluck's method (lecithin/sphingomyelin ratio ( L S )). Using 91 separate amniotic fluid samples, free of meconium and blood contamination, we found that the new method was quick and easy to perform. Thirty-one neonates were delivered within 48 h of the amniotic fluid sampling and the percentage of correct prediction of respiratory distress syndrome (RDS) was 71% with a mature L S ratio and 83% with viscosity < 1.17 cP. In cases with an immature L S ratio (value below 2) the correct prediction of RDS was 64%; with the fluorescence polarization (FP) technique it was 91%. We conclude that the amniotic fluid FP value is a reliable index of fetal lung maturity and risk for developing RDS and has also specific technical and diagnostic advantages over the L S ratio.

Steady shear viscosity measurements of viscoelastic fluids with the falling needle viscometer

Previous measurements by other investigators of the purely viscous properties of viscoelastic fluids using the falling ball viscometer have been shown to yield anomalous results. These occur because the ball falling through the viscoelastic fluid creates a stress field which requires up to one hour to relax to its stress free state before another ball can be dropped. This is experimentally inconvenient. To further investigate this effect for a variety of viscometers, time interval measurements were made on a viscoelastic fluid (AP-273 Separan) using falling ball, falling needle and rotating cylinder viscometers. Although the falling ball measurements showed considerable time interval effects, the falling needle and rotating cylinder measurements did not. Thus the falling needle and rotating cylinder viscometers can be used to conveniently measure the steady shear viscosity of viscoelastic fluids.

細線加熱法による流体の粘度測定

細線加熱法による流体の粘度測定

Simple torque magnetometer for anisotropy measurements in magnetic thin-film media

A simple and novel torque magnetometer for the magnetic anisotropy measurements of magnetic thin-film samples is described. A Brookfield LVTD viscometer, normally used in the viscosity measurements of liquids and fluids, is utilized as a torque measuring device. A HP series 310 computer along with the HP 7090 measurement plotting system interfaced to the torque magnetometer perform data acquisition, any calculations required for data correction, and plotting of the torque curves.

Wall Slip Corrections for Couette and Parallel Disk Viscometers

Often for slurries, gels, emulsions, and foams inhomogeneous fluid properties at solid boundaries create “apparent wall slip.” The reduced fluid viscosity at the boundary creates a thin layer of fluid having a large velocity gradient that can be treated as a “slipping layer”. In measurements of fluid viscosity it is necessary to correct for wall slip to determine the true deformation experienced by the bulk of the sample and the true viscosity. The classic earlier techniques for capillaries and Couette geometries were first presented by Mooney. We present a new analysis of the Couette geometry that requires only two measurements rather than the three used by Mooney. We also present a new analysis for flow between rotating parallel disks. The parallel disk geometry has several experimental advantages for measuring fluid viscosities in the presence of wall slip. The analysis of experimental data on a clay suspension and oil‐in‐water emulsion are presented to demonstrate these new techniques.

Experimental examination of the room temperature hydrodynamics and electrochemical current‐voltage behaviour of the Bi‐terminated vibrating wire electrode

AbstractAn experimental study was made of the room temperature hydrodynamics and current‐voltage (I‐V) behaviour of a bi‐terminated transverse oscillating resonant electrode using an adaptation of the electromagnetically‐driven vibrating wire technique recently developed for precise viscosity measurements of cryogenic fluids. For argon, nitrogen, as well as dilute electrolytes, the shapes of the in‐phase and quadrature resonance lines agreed with lines obtained by computer simulation. Although such peaks exhibited shorter heights than predicted (probably due to dispersion or some energy loss to the end terminations), observed peak areas agreed with theory. Use of either 50‐μm diameter platinum or tungsten wires as working electrodes in three‐electrode voltammetry yielded quite well‐defined I‐V curves for reduction of dilute ferricyanide and iodate as test systems, with Fe(CN)6−3 exhibiting near‐Nernstian reversibility at the tungsten wire. Well‐shaped I‐V curves were also obtained for lead (II) reduction on oxide‐free platinum. Resonant platinum wires clad with lead films produced by controlled potential deposition yielded, as expected, an advantageous negative shift in potential for H+ reduction. Because the mechanical properties of soft or low tensile strength metals deny their direct use as resonant electrodes, clad wires, on the other hand, should enable electrochemical, corrosion, and surface studies of such materials to be accomplished under rather precisely controlled conditions.