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1

A two-layered blood flow model of Bingham type non-Newtonian fluid

Das K., Jana S.

International Journal of Applied Mechanics and Engineering

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2012

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Vol. 17, no. 1

17-26

EN

In the present paper, a two layered blood flow model through a cylindrical tube of a Bingham type non-Newtonian fluid is considered. The relative coefficients of viscosity for peripheral and core layer are determined and their nature is shown graphically for different values of the maximum hematocrit, shape parameter, etc.

2

A mathematical model for blood flow through straight artery of slightly non-circular cross-section

Poria S., Dey K. N., Mazumdar H. P.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 1

261-275

EN

In this paper, a model is presented for investigating some hydrodynamic characteristics of blood flow through a large arterial vessel of slightly non-circular cross section. The viscosity of blood is assumed non-uniform due to a distribution of erythrocytes (red cells). The effects of such variation of viscosity on the hydrodynamic flow characteristics, e.g., velocity profiles, volumetric flow rate and shear stress distribution are investigated. These characteristics are then compared with the similar results obtained for the case of blood flow through the corresponding tube of circular cross section.

3

Non-invasive measurement of blood hematocrit in artery

Secomski W., Nowicki A., Guidi F., Tortoli P., Lewin P.A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2005

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Vol. 53, nr 3

245-250

EN

Objective: The goal of this work was to develop a clinically applicable method for non-invasive acoustic determination of hematocrit m VIVO. Methods: The value of hematocrit (HCT) was determined initially in vitro from the pulse-echo measurements of acoustic attenuation. The testing was carried out using a laboratory setup with ultrasound transducer operating at 20 MHz and employing human blood samples at the temperature of 37°C. The attenuation coefficient measurements in blood in vitro and in vivo were implemented using multi-gated (128-gates), 20 MHz pulse Doppler flow meter. The Doppler signal was recorded in the brachial artery. Both in vitro and in vivo HCT data were compared with those obtained using widely accepted, conventional centrifuge method. Results: The attenuation coefficient in vitro was determined from the measurements of 168 samples with hematocrit varying between 23.9 and 51.6%. Those experiments indicated that the coefficient increased linearly with hematocrit. The HCT value was obtained from the 20 MHz data using regression analysis. The attenuation (0 was determined as a 42.14 + 1.02 . HCT (Np/m). The corresponding standard deviation (SD), and the correlation coefficient were calculated as SD = 2.4 Np/m, and R = 0.9, (p < 0.001 ), respectively The absolute accuracy of in vivo measurements in the brachial artery was determined to be within +-5% HCT. Conclusions: The method proposed appears to be promising for in vivo determination of hematocrit as 5% error is adequate to monitor changes in patients in shock or during dialysis. It was found that the multigate system largely simplified the placement of an ultrasonic probing beam in the center of the blood vessel. Current work focuses on enhancing the method's applicability to arbitrary selected vessels and reducing the HCT measurement error to well below 5%.