scholarly journals Simulations of Frictional Losses in a Turbulent Blood Flow Using Three Rheological Models

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Human Blood ◽  
Blood Flow Rate ◽  
Momentum Equation ◽  
Frictional Loss ◽  
Rheological Models ◽  
Frictional Losses ◽  
Yield Shear Stress ◽  
Main Challenge

Blood flow rate is a crucial factor in transporting an oxygen and depends on several parameters like heart pressure, blood properties like density and viscosity, frictional loss and diameter and shape of vein. Frictional loss is a main challenge of current engineering. Therefore, simulation of dependence of blood properties on frictional loss is very important. When blood properties are considered the first step is to find proper rheological model. It is well known that human blood demonstrates a yield shear stress. Therefore, the research is focused on simulating frictional losses in a turbulent flow of human blood, which demonstrates a yield stress. Three arbitrarily chosen rheological models were considered, namely Bingham, Casson and Herschel-Bulkley. Governing equations describing turbulent blood flow were developed to axially symmetrical an aorta. The mathematical model constitutes three partial differential equations, namely momentum equation, kinetic energy of turbulence and its dissipation rate. The main objective of the research is examining influence of the yield shear stress on frictional losses in a human blood in an aorta when flow becomes turbulent. Simulation of blood flow confirmed marginal influence of a yield shear stress on frictional losses when flow becomes turbulent. Results of simulations are discussed and final conclusions are stated.

Is the Maturation of Arteriovenous Fistulas a Mechanical or Biological Problem?

2016 ◽  
Author(s):  
Daniel Jodko ◽  
Damian Obidowski ◽  
Piotr Reorowicz ◽  
Krzysztof Jozwik
Keyword(s):  
High Pressure ◽  
Blood Flow ◽  
Shear Stress ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Average Diameter ◽  
Patient Specific ◽  
Maturation Process ◽  
Arteriovenous Fistulas ◽  
Biological Problem

During the maturation the high pressure blood from the artery inflows directly to the vein, extends its diameter, and finally the blood flow rate in the vein is even 500-times greater than normal one. The changes of the wall shear stress (WSS) in the vein are thought to play a key role in the remodelling of its wall. However, this process is still not well understood. The aim of this paper is to show an innovative approach for modelling of the vein deformation during the maturation process of a-v fistulas. Dilation of the vein was modelled as two-step complex biomechanical process. The obtained results concerning final diameter of the vein are compared with average diameter obtained for large group of patients. Moreover, this study shows the changes in the flow rate and the WSS that occur after maturation in the patient-specific fistula.

scholarly journals Physical and Chemical Characterization of Drag Reducing Polymer Based on Polyvinylpyrrolidone (PVP) in Human Blood Flow

2021 ◽  
Vol 8 (2) ◽  
pp. 20218207
Author(s):  
Akram Jassim Jawad ◽  
Auda J. Braihi
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Shear Rate ◽  
Human Blood ◽  
Chemical Characterization ◽  
Tissue Perfusion ◽  
Moderate Intensity ◽  
Mixing Efficiency ◽  
Reduced Pressure ◽  
Drag Reducing Polymer

A new attempt to use Polyvinylpyrrolidone (PVP) as a bio-drag reducing polymer agent for human blood flow has been studied. PVP was added at 0, 500, 750 and 1000 part per million (ppm) and mixed with human blood at room temperature for 2 minutes. Then, a cone on plate rheometer was used to investigate the effectiveness of PVP agent on blood rheological properties. The results showed significant effecting of PVP on blood fluidity characteristics, where the viscosity decreased as the PVP content increased or as a shear rate increased. For a certain shear rate, the shear stress decreased as PVP content increased. These changes will lead to increased mixing efficiency within the capillaries, increased oxygen transportation, increased tissue perfusion, modified red blood cells (RBCs) distribution, reduced pressure drop gradients, enhanced turbulent flow tendency, enhanced viscoelasticity nature of the blood and its strengthened non-Newtonian pattern. Also, the results showed that the viscosity-shear stress relationships become more linear at higher PVP concentrations. PVP addition caused no shifting in UV-absorbing positions and only moderate intensity changing. Atomic force microscopy (AFM) parameters provide other indicators about the role of PVP as a drag reduction agent for blood flow, where all of the amplitude, hybrid and special parameters decreased significantly.

A study of the deformability of red blood cells of a teleost fish, the yellowtail (Seriola quinqueradiata), and a comparison with human erythrocytes

1982 ◽  
Vol 96 (1) ◽  
pp. 209-220
Author(s):  
G. M. Hughes ◽  
Y. Kikuchi ◽  
H. Watari
Keyword(s):  
Blood Flow ◽  
Red Blood Cells ◽  
Human Blood ◽  
Blood Cells ◽  
Blood Flow Rate ◽  
Blood Flows ◽  
Human Red Blood Cells ◽  
Seriola Quinqueradiata ◽  
Flow Through ◽  
Environmental Temperatures

The blood of a carangid fish, the yellowtail (Seriola quinqueradiata) has been studied with particular reference to the deformability properties of the red blood cells. The rate at which blood flows through a Nuclepore filter containing 5 micrometers pores has been determined under the same conditions that have been used with human blood. Marked differences were found in the flow of yellowtail blood which depended on the particular way in which the blood had been sampled. Such differences seem to be due to a sensitivity of fish red blood cells to their environmental conditions. Blood flow through filters is temperature-dependent, the rate increasing with a rise in temperature. Measurements made at 37 degrees C gave values which were similar to those normally obtained for human red blood cells, in spite of their greater dimensions (10.4 × 6.8 × 3.4 micrometers), and nucleated nature. It was also found that the blood flow rate of human blood was slower than that of yellowtail blood when measured at the normal environmental temperatures (15 degrees C) for these fish.

scholarly journals Blood flow rate and wall shear stress in seven major cephalic arteries of humans

2019 ◽  
Vol 236 (3) ◽  
pp. 522-530
Author(s):  
Roger S. Seymour ◽  
Qiaohui Hu ◽  
Edward P. Snelling
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Wall Shear

Sensitivity of patient-specific numerical simulation of cerebal aneurysm hemodynamics to inflow boundary conditions

2007 ◽  
Vol 106 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Prem Venugopal ◽  
Daniel Valentino ◽  
Holger Schmitt ◽  
J. Pablo Villablanca ◽  
Fernando Viñuela ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Flow Rate ◽  
Artery Aneurysm ◽  
Blood Flow Rate ◽  
Patient Specific ◽  
Stress Distributions ◽  
Flow Rates

Object Due to the difficulty of obtaining patient-specific velocity measurements during imaging, many assumptions have to be made while imposing inflow boundary conditions in numerical simulations conducted using patient-specific, imaging-based cerebral aneurysm models. These assumptions can introduce errors, resulting in lack of agreement between the computed flow fields and the true blood flow in the patient. The purpose of this study is to evaluate the effect of the assumptions made while imposing inflow boundary conditions on aneurysmal hemodynamics. Methods A patient-based anterior communicating artery aneurysm model was selected for this study. The effects of various inflow parameters on numerical simulations conducted using this model were then investigated by varying these parameters over ranges reported in the literature. Specifically, we investigated the effects of heart and blood flow rates as well as the distribution of flow rates in the A1 segments of the anterior cerebral artery. The simulations revealed that the shear stress distributions on the aneurysm surface were largely unaffected by changes in heart rate except at locations where the shear stress magnitudes were small. On the other hand, the shear stress distributions were found to be sensitive to the ratio of the flow rates in the feeding arteries as well as to variations in the blood flow rate. Conclusions Measurement of the blood flow rate as well as the distribution of the flow rates in the patient's feeding arteries may be needed for numerical simulations to accurately reproduce the intraaneurysmal hemodynamics in a specific aneurysm in the clinical setting.

Yield shear stress and disaggregating shear stress of human blood

2014 ◽  
Vol 26 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Jinmu Jung ◽  
Byoung-Kwon Lee ◽  
Sehyun Shin
Keyword(s):  
Shear Stress ◽  
Human Blood ◽  
Yield Shear Stress

On the Application of a Constitutive Equation for Whole Human Blood

1990 ◽  
Vol 112 (2) ◽  
pp. 198-206 ◽  
Author(s):  
C. M. Rodkiewicz ◽  
Prawal Sinha ◽  
J. S. Kennedy
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Constitutive Equation ◽  
Newtonian Fluid ◽  
Human Blood ◽  
Bingham Fluid ◽  
Stress Distributions ◽  
Pulsatile Blood Flow ◽  
Governing Equations

In consideration of the pulsatile blood flow in a conduit, the consitutive equation for the whole human blood of F. J. Walburn and D. J. Schneck (Biorheology, Vol. 13, 1976, pp. 201-210) is utilized. Governing equations are solved numerically yielding the velocity and the shear stress distributions. These results are discussed and compared with the Newtonian fluid, Casson’s fluid, and Bingham fluid applications.

scholarly journals Laser Doppler Flow Meter: A New Approach for Calculation of Human Blood Flow Rate

2015 ◽  
Vol 127 (17) ◽  
pp. 35-38
Author(s):  
Nikhil A. ◽  
K. Sujatha ◽  
Ashlesha Kulkarni
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Human Blood ◽  
Blood Flow Rate ◽  
Laser Doppler ◽  
Flow Meter ◽  
Laser Doppler Flow ◽  
New Approach ◽  
Doppler Flow

Factors Influencing Leukocyte Adherence in Microvessels

1977 ◽  
Vol 38 (04) ◽  
pp. 0823-0830 ◽  
Author(s):  
Mayrovttz N. Harvey ◽  
Wiedeman P. Mary ◽  
Ronald F. Tuma
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Tissue Injury ◽  
Threshold Value ◽  
In Vivo Studies ◽  
Leukocyte Adherence ◽  
Rolling Velocity ◽  
Subsequent Behavior ◽  
Flow Stasis

SummaryIn vivo studies of the microcirculation of an untraumatized and unanesthetized animal preparation has shown that leukocyte adherence to vascular endothelium is an extremely rare occurrence. Induction of leukocyte adherence can be produced in a variety of ways including direct trauma to the vessels, remote tissue injury via laser irradiation, and denuding the epithelium overlying the observed vessels. The role of blood flow and local hemodynamics on the leukocyte adherence process is quite complex and still not fully understood. From the results reported it may be concluded that blood flow stasis will not produce leukocyte adherence but will augment pre-existing adherence. Studies using 2 quantitative measures of adherence, leukocyte flux and leukocyte velocity have shown these parameters to be affected differently by local hemodynamics. Initial adherence appears to be critically dependent on the magnitude of the blood shear stress at the vessel wall as evidenced by the lack of observable leukocyte flux above some threshold value. Subsequent behavior of the leukocytes as characterized by their average rolling velocity shows no apparent relationship to shear stress but, for low velocities, may be related to the linear blood velocity.

Basic study on estimation method of wall shear stress in common carotid artery using blood flow imaging

2020 ◽  
Vol 59 (SK) ◽  
pp. SKKE16 ◽  
Author(s):  
Ryo Nagaoka ◽  
Kazuma Ishikawa ◽  
Michiya Mozumi ◽  
Magnus Cinthio ◽  
Hideyuki Hasegawa
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Common Carotid Artery ◽  
Estimation Method ◽  
Flow Imaging ◽  
Basic Study ◽  
Blood Flow Imaging ◽  
Wall Shear
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