Blood Flow In Stenotic Arteries Research Articles

Blood Flow Modeling in Constricted Arteries Under Body Acceleration and Wall Slip Using Two-Layered Bingham Plastic Fluid

Analysis is done on a two-layered Bingham Plastic model of restricted, thin arteries with periodic body acceleration. The model essentially consists of a centre layer with a core of suspended red blood cells and an outer layer with a peripheral plasma layer. It has been assumed that the rheology of blood in the core region has been classified as a Newtonian fluid with the PPL and a non-Newtonian fluid obeying the law of Bingham plastic model. This model has been used to investigate how blood flow in stenotic arteries is affected by body acceleration, the non-Newtonian character of blood, and a velocity slip at the wall. Analytical equations for axial velocity, flow rate, wall shear stress, and apparent viscosity are produced by using the perturbation method, and their variations with respect to various parameters are shown in the figures and explained in this article. Due to a wall slip, it is seen that while velocity and flow rate rise, effective viscosity falls. The impact of body acceleration significantly increases flow rates and speed. The physiological effects of this theoretical modelling for blood flow conditions are also briefly looked at.

Magnetohydrodynamic blood flow study in stenotic coronary artery using lattice Boltzmann method

Background and objective: Cardiovascular diseases such as atherosclerosis are the first engender of death in the world. The malfunctioning of cardiovascular system is attributed mainly to hemodynamics. However, blood magnetic properties are of major haemodynamic interest, with significant clinical applications. The aim of this work is to study numerically the effect of high magnetic field on blood flow in stenotic artery.Methods: In this paper, a double population D2Q9 lattice Boltzmann model is proposed. Velocity and magnetic field are both solved using Lattice Boltzmann method with single relaxation time. Blood is considered homogeneous and Newtonian bio-magnetic fluid. The results of the proposed model are compared and validated by recent numerical and experimental studies in the literature and show good agreement. In this study, simulations are carried out for both hydrodynamics and magneto-hydrodynamics. For the magneto-hydrodynamic case, five values of Hartmann number of 10, 30, 50, 75 and 100 at Reynolds number of 400, 600 and 800 are investigatedResults: The results show that velocity and recirculation zone increase with the increase of the degree of stenosis and Reynolds number. In addition, a considerable decrease in velocity, recirculation zones and pressure drop across the stenotic artery is noticed with the increase of Hartmann number.Conclusion: The suggested model is found to be effective and accurate in the treatment of magneto-hydrodynamic blood flow in stenotic artery. The found results can be used by clinicians in the treatment of certain cardiovascular disorders and in regulating blood flow movement, especially during surgical procedures.

The Influence of Dynamic Blood Viscosity on Coronary Blood Flow in Stenotic Artery

The Influence of Dynamic Blood Viscosity on Coronary Blood Flow in Stenotic Artery

Oscillatory Viscoelastic Model of Blood Flow in Stenotic Artery

An analytic solution for the two-layered model of pulsatile blood flow in stenotic arteries is discussed. The blood flow in narrow arteries is assumed to obey the two-fluid model: non-Newtonian viscoelastic as Jeffrey fluid in core region, and Newtonian as plasma fluid in peripheral region. The present study is aimed to develop an oscillatory viscoelastic model of blood flow and obtain the analytic expressions for velocity of pulsatile blood flow in a stenotic artery. The velocity of pulsatile blood flow is used to discuss the wall shear stress and volume flow rate through stenotic artery and to relate relaxation time, retardation time, height of the stenosis with the velocity, volume flow rate and wall shear stress. The solution of the model boundary value problem is obtained by the method of special functions under the assumption of steady oscillations. It is found that the velocity is directly proportional to relaxation time and on the other hand retardation time is inversely proportional. For non-zero time period, the wall shear stress increases as relaxation time increases and decreases as retardation time increases. It reveals a significant influence of relaxation and retardation time on oscillatory blood flow in stenotic artery under the pathological state of cardiovascular disease.

A Numerical Simulation of Pressure Variation in Arteries affected by Stenosis

This paper is mainly concerned with the effect of pressure variations in different dilations of stenotic arteries. In this study, we numerically analyzed unsteady blood flow in stenotic arteries with constrictions 25%, 50%, 75% and 90%. A finite volume method is used to investigate flow in a tube with an occlusion. Using computational fluid dynamics techniques, hemodynamic factors such as velocity, pressure and streamline patterns are investigated. Wall shear stress and strain are numerically analyzed. Results are compared and validated. The study of unsteady flow reveals correlation between regions of recirculation and the lesion's location. Detection and quanti?cation of stenosis serve as the root for surgical interference. These techniques based on computer flow study are important for understanding the relationship between hemodynamic parameters and hazard of rupture.

Coupling of shear-circumferential stress pulses investigation through stress phase angle in FSI models of stenotic artery using experimental data.

Many cardiovascular diseases are closely associated with hemodynamic parameters. The main purpose of this study is mimicking a physiological blood flow in stenotic arteries to provide an understanding of hemodynamic parameters. An experimental setup was designed to produce original pulsatile flow and measure pressure pulse waves through a compliant tube. Moreover, a numerical model considering fluid-solid interaction was developed to investigate wall shear stress and circumferential stress waves, based on the results of the experiments. Results described elevated mean pressure by increasing stenosis severity especially at the critical obstacle of 50%, which the pressure rose significantly and raised up by 10mm Hg that may cause damage in endothelial cells. Increasing in stenosis severity led to: more negative wall shear stress and more oscillation of shear stress at the post-stenotic region and also more absolute value of angular phase difference between wall shear stress and circumferential stress waves at the stenotic throat. All of the aforementioned parameters determinant the endothelial cell pathology in predication of potential sites of progression of atherosclerotic plaques. Therefore, results can be applied in study of plaque growth and mechanisms of arterial remodeling in atherosclerosis.

Numerical investigation of the hydrodynamic parameters of blood flow through stenotic descending aorta.

In this study, the blood flow passing through a three-dimensional geometrically realistic stenosis is investigated both experimentally and numerically. Although the blood flow in stenotic arteries has been extensively studied in the past few decades, not much work has been focused on irregularity of stenosis. Thus, a model of an irregular stenotic descending aorta is used in this work. Due to the irregularity of stenosis model, the governing differential equations for continuity and momentum are solved numerically using finite-volume/finite-difference techniques in the generalized body-fitted coordinates. In order to verify the numerical results, the experimental measured pressure drops are compared with the numerical result. In addition, an improved method for nearly orthogonal grid generation is presented in numerical study. The grid generating system is based on the solution of a set of partial differential equations with finite difference discretization. Numerical calculations are performed to examine the effect of 55% (ratio between cross-sectional area at upstream and stenosis) irregular stenosis on the hemodynamic characteristics such as flow separation zone, wall shear stress and pressure drop. The maximum calculated wall shear stress is related to the maximum velocity gradient due to minimum cross-sectional area at the neck of stenosis. In addition, the pressure is shown as an important characteristic that is effecting on the resistance against the flow in the artery. Based on our results, the 55% irregular constriction is considered critical unlike the studies that have believed the reduction, which is greater than 75% become significant.

Computational Modeling and Analysis of the Hydrodynamic Parameters of Blood through Stenotic Artery

Abstract In this paper, we are considering the blood flow passing through a three-dimensional geometrically realistic stenosis is investigated both experimentally and numerically. Although the blood flow in stenotic arteries has been extensively studied in the past few decades, not much work has been focused on irregularity of stenosis. Therefore, a computational model of an irregular stenotic descending aorta is used in this research work. The governing equations are solved numerically using finite-volume/finite-difference techniques in the generalized body-fitted coordinates system. The grid generating system is based on solution of a set of partial differential equations with finite difference discretization.

Simulation of transient blood flows in the artery with an asymmetric stenosis

This article focuses on the transient behaviour of blood flow in stenotic arteries. Human blood is modelled as an incompressible non-Newtonian fluid. A numerical technique based on the finite element method is developed to simulate the blood flow taking into account of the transient periodic behaviour of the blood flow in cardiac cycles. The flow pattern, the distribution of pressure and the wall shear stresses, are computed. The results show that the pulsatile pressure and the time variation of wall shear rate have patterns similar to that for the pulsatile velocity during the cardiac cycles. On the back toe of the stenosis there exists a small recirculation region which causes the direction of the wall shear stress in some part to oscillate, likely leading to atherosclerotic disease. The back toe is thus an ideal location for applying a clot dissolving drug. References D. N. Ku, Blood flow in arteries, Annual Review of FLuid Mechanics 29 (1997) 399--434. D. Mann and J. Tarbell, Flow of non-Newtonian blood analog fluids in rigid curved and straight artery models, Biorheology 27 (1990) 711--733. M. Grigioni, C. Daniele and G. D'Avenio, The role of wall shear stress in unsteady vascular dynamics, Progress in Biomedical Research 7 (3) (2002) 204--212. K. B. Chandran, J. H. Mun, K. K. Choi, J. S. Chen, A. Hamilton, A. Nagaraj and D. D. McPherson, A method for in-vivo analysis for regional arterial wall material property alterations with alterosclerosis: preliminary results, Medical Engineering and Physics 25 (2003) 289--298. M. Bonert, J. G. Myers, S. Fremes, J. Williams and C. R. Ethier, A numerical study of blood flow in coronary artery bypass graft Side-to-Side Anastomoses, in Annals of Biomedical Engineering 30 (2002) 599--611. D. Y. Fei, J. D. Thomas and S. E. Rittgers, The effect of angle and flow rate upon hemodynamics in distal vascular graft anastomoses: a numerical model study, Journal of Biomechanical Engineering 116 (1994) 331--336. M. H. Song, M. Sato, Y. Ueda, Three dimensional simulation of coronary artery bypass grafting with the use of computational fluid dynamics, Surg Today 30(2000), 993--998. B. Wiwatanapataphee, D. Poltem, Y. H. Wu and Y. Lenbury, Simulation of pulsatile flow of blood in stenosed coronary artery bypass with graft, Mathematical Biosciences 3 (2) (2006) 371--383. S. Glagov and C. K. Zarins and D. P. Giddens and D. N. Ku, Hemodynamics and Atherosclerosis, Insights and perspectives gained from studies of human arteries, Archieves of Pathology and Laboratory Medicine 112 (1988) 1018--1031.

Effect of a magnetic field on the resistance to blood flow through stenotic artery

In this paper, we have analyzed the effect of external magnetic field on blood flow in stenotic artery. We have taken the effect of magnetic field in transverse direction to blood flow, and considered the viscosity of blood as radial co-ordinate dependent i.e. μ = μ 0 r R 0 - M . We have the solve the non-linear pressure equation with the help of boundary conditions and series method. We have found the results for velocity resistance to the blood flow. These results are displayed graphically for different magnetic field. Thus, the magnetic field can be used for clinical purposes.

The influence of grain size on the ductility of micro-scale stainless steel stent struts

Vascular stents are used to restore blood flow in stenotic arteries, and at present the implantation of a stent is the preferred revascularisation method for treating coronary artery disease, as the introduction of drug eluting stents (DESs) has lead to a significant improvement in the clinical outcome of coronary stenting. However the mechanical limits of stents are being tested when they are deployed in severe cases. In this study we aimed to show (by a combination of experimental tests and crystal plasticity finite element models) that the ductility of stainless steel stent struts can be increased by optimising the grain structure within micro-scale stainless steel stent struts. The results of the study show that within the specimen size range 55 to 190 microm ductility was not dependent on the size of the stent strut when the grain size maximised. For values of the ratio of cross sectional area to characteristic grain length less than 1,000, ductility was at a minimum irrespective of specimen size. However, when the ratio of cross sectional area to characteristic grain length becomes greater than 1,000 an improvement in ductility occurs, reaching a plateau when the ratio approaches a value characteristic of bulk material properties. In conclusion the ductility of micro-scale stainless steel stent struts is sensitive to microstructure and can be improved by reducing the grain size.

Simulating cyclic artery compression using a 3D unsteady model with fluid–structure interactions

High pulsating blood pressure and severe stenosis make fluid–structure interaction (FSI) an important role in simulating blood flow in stenotic arteries. A three-dimensional nonlinear model with FSI and a numerical method using GFD are introduced to study unsteady viscous flow in stenotic tubes with cyclic wall collapse simulating blood flow in stenotic carotid arteries. The Navier–Stokes equations are used as the governing equations for the fluid. A thin-shell model is used for the tube wall. Interaction between fluid and tube wall is treated by an incremental boundary iteration method. Elastic properties of the tube wall are determined experimentally using a polyvinyl alcohol hydrogel artery stenosis model. Cyclic tube compression and collapse, negative pressure and high shear stress at the throat of the stenosis, flow recirculation and low shear stress just distal to the stenoses were observed under physiological conditions. These critical flow and mechanical conditions may be related to platelet aggregation, thrombus formation, excessive artery fatigue and possible plaque cap rupture. Computational and experimental results are compared and reasonable agreement is found.

The effect of hemorrhage and dextran infusion on blood flow in stenotic arteries

The effect of hemorrhage and dextran infusion on blood flow in stenotic arteries