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Viscosity Measurement Using Optical Tracking of Free Fall in Newtonian Fluid

100%
Kheloufi N., Lounis M.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1
123-127
EN
This paper presents a novel method in viscosity assessment using a tracking of the ball moving in Newtonian fluid. The movement of the ball is assimilated to a free fall within a tube containing liquid of whose we want to measure a viscosity. In classical measurement, height of fall is estimated directly by footage where accuracy is not really considered. Falling ball viscometers have shown, on the one hand, a limit in the ball falling height measuring, on the other hand, a limit in the accuracy estimation of velocity and therefore a weak precision on the viscosity calculation of the fluids. Our technique consist to measure the fall height by taking video sequences of the ball during its fall and thus estimate its terminal velocity which is an important parameter for cinematic velocity computing, using the Stokes formalism. The time of fall is estimated by cumulating time laps between successive video sequences which mean that we can finally estimate the cinematic viscosity of the studied fluid.
2
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Analysis of Complex Viscosity in a Group of Patients with Circulation Disorders

70%
Marcinkowska-Gapińska A., Kowal P.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1A
A-54-A-56
EN
Rheology of viscoelastic fluids is a complex phenomenon. Full blood is an example of a body fluid of non-Newtonian character with pronounced viscoelastic properties. Blood flow in the circulatory system depends not only on the physical and physico-chemical properties of blood but also on the structure and properties of the vascular system. Blood viscosity is one of the most important factor determining the blood flow. Its value depends on the shear rate, hematocrit, erythrocyte aggregability and deformability, and on the plasma viscosity and composition. In the course of the investigation we utilized oscillatory methods, called also dynamic mechanical analysis. The technique principle is based on the measurement of the amplitude and phase of oscillations of the sample subject to a harmonic force with certain amplitude and frequency. The results of dynamic mechanical analysis were used to determine the viscoelastic properties of blood samples. We performed also the standard flow curve measurements of the blood plasma samples, that is shear stress as a function of shear rate in the rotary mode. All measurements were performed by means of a Contraves LS-40 rheometer on blood samples taken from two groups of patients. One group contained patients after heart attack, while the second one - after cerebral infarction. In none of the groups the patients were in an acute state. Information obtained from oscillatory measurements indicate increased erythrocyte aggregability in both groups of patients.
3
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Dynamic Viscosity of Aluminum Oxide-Ethylene Glycol (Al₂O₃-EG) Nanofluids

70%
Żyła G., Fal J., Gizowska M., Witek A., Cholewa M.
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EN
The paper presents the results of measurements of rheological properties of ethylene glycol (EG) based aluminum oxide (Al₂O₃) nanofluids. The nanofluids have been produced by two-step method with the use of commercially available nanoparticles. Dynamic viscosity curves and dependence of viscosity on temperature for these materials have been measured. It has shown that with higher concentration of nanoparticles in the suspension, these nanofluids exhibit the non-Newtonian flow and it can be considered as shear-thinning liquids. The effect of temperature on the dynamic viscosity in Al₂O₃-EG nanofluids can be modelled with the use of Vogel-Fulcher-Tammann expression.
4
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Analysis of the Effect of Magnetostimulation on Viscoelastic Properties of Blood in Patients with Lasting Pain

61%
Marcinkowska-Gapińska A., Kowal P.
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vol. 125
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issue 4A
A-24-A-26
EN
The aim of the current work was to analyze the influence of alternating magnetic field on the viscoelastic properties of blood in vivo in patients with lasting pain problems. Oscillatory techniques, also called the dynamic mechanical analysis, have been used in the current work to study the viscoelastic properties of blood. The blood samples were collected from patients of a neurological ward complaining about spinal cord and lower limbs pain. Altogether 25 patients took part in the study. A blood sample was collected from each patient twice: before the magnetostimulation and after five treatments. For each blood sample, the hematocrit value was measured using the standard method. Plasma viscosity and the complex whole blood viscosity were measured by means of a rotary-oscillating rheometer Contraves LS40. Magnetic field was generated by the instrument Viofor JPS and the magnetostimulation treatments were performed using different programs. The analysis of the results included estimation of the hematocrit value, plasma viscosity, complex whole blood viscosity and its components: viscous and elastic viscosity at four chosen amplitudes of the shear rate as a function of the applied treatment program. The results obtained in the study suggest that rheological properties of blood change depending on the applied magnetostimulation program.
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