scholarly journals Domain decomposition modeling of carotid artery stenosis based on 3D rotational angiography

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110180
Author(s):  
Qinghe Yao ◽  
Hongkun Zhu
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Domain Decomposition ◽  
Stokes Equations ◽  
Computational Study ◽  
Domain Decomposition Method ◽  
Swine Model ◽  
Wall Shear

An experiment-based computational study that helps analyze blood flow behavior and wall shear stress (WSS) distribution is reported in this work. Large scale numerical analysis of hemodynamics in swine-specific stenosed carotid artery based on in vivo surgery is presented. A pressure stabilized domain decomposition method is used to symmetrize the linear systems of Navier-Stokes equations and the convection-diffusion equation. A numerical expression of swine blood flow and a detailed swine carotid vessel model with stenosis are newly proposed, and the empirical function of WSS was validated for the swine model. Two wall models, a rigid and another elastic, are compared in precisely modelling for pathological analysis of vascular disease like carotid atherosclerosis and hemangioma. The flexible wall performs better in representing experimental conditions while the stern wall is much more efficient. Numerical results show that the stenosis has a great influence on the behavior and characters of blood and its subsequent affect the WSS of the vessel; further details show how stenosis affect the distribution and magnitude of wall shear stress in an artery which lay a foundation for further medical study.

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

scholarly journals Numerical Simulation of Dispersed Particle-Blood Flow in the Stenosed Coronary Arteries

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Mongkol Kaewbumrung ◽  
Somsak Orankitjaroen ◽  
Pichit Boonkrong ◽  
Buraskorn Nuntadilok ◽  
Benchawan Wiwatanapataphee
Keyword(s):  
Numerical Simulation ◽  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Stokes Equations ◽  
Spherical Shape ◽  
Shear Stresses ◽  
Wall Shear

A mathematical model of dispersed bioparticle-blood flow through the stenosed coronary artery under the pulsatile boundary conditions is proposed. Blood is assumed to be an incompressible non-Newtonian fluid and its flow is considered as turbulence described by the Reynolds-averaged Navier-Stokes equations. Bioparticles are assumed to be spherical shape with the same density as blood, and their translation and rotational motions are governed by Newtonian equations. Impact of particle movement on the blood velocity, the pressure distribution, and the wall shear stress distribution in three different severity degrees of stenosis including 25%, 50%, and 75% are investigated through the numerical simulation using ANSYS 18.2. Increasing degree of stenosis severity results in higher values of the pressure drop and wall shear stresses. The higher level of bioparticle motion directly varies with the pressure drop and wall shear stress. The area of coronary artery with higher density of bioparticles also presents the higher wall shear stress.

Effects of blood flow characteristics on rupture of cerebral aneurysm: Computational study

2021 ◽  
pp. 2150143
Author(s):  
Xiao-Yong Shen ◽  
M. Barzegar Gerdroodbary ◽  
Amin Poozesh ◽  
Amir Musa Abazari ◽  
S. Misagh Imani
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
High Risk ◽  
Wall Shear Stress ◽  
Flow Pattern ◽  
Cerebral Aneurysm ◽  
Computational Study ◽  
Fluid Dynamic ◽  
Aneurysm Wall ◽  
Wall Shear

In recent decades, cardiovascular disease and stroke are recognized as the most important reason for the high death rate. Irregular bloodstream and the circulatory system are the main reason for this issue. In this paper, Computational Fluid dynamic method is employed to study the impacts of the flow pattern inside the cerebral aneurysm for detection of the hemorrhage of the aneurysm. To achieve a reliable outcome, blood flow is considered as a non-Newtonian fluid with a power-law model. In this study, the influence of the blood viscosity and velocity on the pressure distribution and average wall shear stress (AWSS) are comprehensively studied. Moreover, the flow pattern inside the aneurysm is investigated to obtain the high-risk regions for the rupture of the aneurysm. Our results indicate that the wall shear stress (WSS) increases with increasing blood flow velocity. Furthermore, the risk of aneurysm rupture is considerably increased when the AWSS increases more than 0.6. Indeed, the blood flow with high viscosity expands the high-risk region on the wall of the aneurysm. Blood flow indicates that the angle of the incoming bloodstream is substantially effective in the high-risk region on the aneurysm wall. The augmentation of the blood velocity and vortices considerably increases the risk of hemorrhage of the aneurysm.

Analysis of Blood Flow Patterns to Estimate Atherosclerosis Formation in the Left Carotid Artery by CFD Simulation

2020 ◽  
Author(s):  
Marzia Momin ◽  
Nusrat Ara ◽  
M. Tarik Arafat
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Cfd Simulation ◽  
Lower Percentage ◽  
Hemodynamic Parameters ◽  
Left Carotid Artery ◽  
Bifurcation Angle ◽  
Wall Shear

Abstract The purpose of this computational fluid dynamics (CFD) study is to simulate left carotid artery models to evaluate the influence of hematocrit (Hct) level and angle of bifurcation on the formation of atherosclerosis. Bifurcation angle can vary from person to person based on sex, age or diseased condition which has an impact on hemo-dynamic parameters. From the anatomical study, it is seen that the carotid artery bifurcation is the preferential region for atherosclerosis formation. The combination of bifurcation, curvature and diameter change in this bifurcation region causes the blood flow to be complex with recirculation regions and secondary flows which influence hemodynamic changes and the formation of atherosclerosis. Along with the bifurcation angle, the Hct level also influences on changing hemodynamic parameters. As the viscosity of blood is mainly controlled by the Hct level, the hemodynamic parameters of blood are changed on the basis of change in percentage of the Hct level. Therefore, the Hct percentage can act as a risk factor for atherosclerosis formation. We have assessed the probability of vulnerable atherosclerosis formation based on the change of both bifurcation angle and hematocrit level. In this study, three different carotid artery geometries with 40 degree, 48.5 degree, and 63.6 degree angles were simulated at a varying percentage of the Hct level. We discerned these models by using CFD simulation to calculate wall shear stress (WSS), time-averaged wall shear stress (TAWSS) and velocity. The effects of angulation and Hct percentage on the velocity of blood were studied on the plane of the bifurcation region. The carotid artery with 63.6 degree angulation faces more recirculation areas and peak recirculation areas are observed at 25% Hct level. This justifies the reason behind atherosclerosis formation in the artery. We observed low WSS at wider angled models and a high WSS at narrow angled models. WSS value is also affected by the percentage of Hct. In this study, we noticed a lower value of WSS at a lower percentage of Hct which is responsible for atherosclerosis formation. The WSS value of 0.4 Pa was considered as the critical point for the atherosclerosis formation. We also calculated time-averaged wall shear stress (TAWSS) which is similar to the WSS contour plot. Overall, after analyzing the results of velocity, WSS and TAWSS, we concluded that low Hct (around 25% or lower) along with higher bifurcation angle (around 63.6 degree or higher) are more accountable for atherosclerosis formation.

Two-Dimensional Meshless Numerical Modeling of the Blood Flow Within Arterial End-to-Side Distal Anastomoses

2006 ◽  
Author(s):  
Zaher El Zahab ◽  
Eduardo A. Divo ◽  
Alain J. Kassab ◽  
Eric A. Mitteff
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Meshless Method ◽  
Stokes Equations ◽  
Computational Domain ◽  
Two Dimensional ◽  
Point Distribution ◽  
Direct Model ◽  
Wall Shear

In the current paper we introduce the localized meshless method to resolve the two-dimensional blood flow in the vicinity of a peripheral bypass graft end-to-side distal anastomosis. The goal is to incorporate this new numerical technique in extracting the values of the fluid mechanics wall parameters, such as the wall shear stress and the wall shear stress gradients, which are suggested as contributory factors to the growth of post-operative intimal hyperplasia at the anastomosis. The localized meshless method depends on the Hardy Multiquadrics radial basis function to locally expand the flow variables over a set of nodes distributed in the computational domain. An explicit scheme is adapted for the meshless formulation of the laminar incompressible Navier Stokes equations. Our special interest in the localized meshless method arises from its automated point distribution feature that significantly facilitates the pre-processing of the solution. The blood flow is simulated in three different anastomosis model geometries; the conventional or direct model, the Miller Cuff model, and the Taylor Patch model. The results of the current localized meshless numerical method show a great agreement with the results provided by a well-established finite volume method commercial software.

scholarly journals Computational Study of the Blood Flow in Three Types of 3D Hollow Fiber Membrane Bundles

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Jiafeng Zhang ◽  
Xiaobing Chen ◽  
Jun Ding ◽  
Katharine H. Fraser ◽  
M. Ertan Taskin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Hollow Fiber ◽  
Computational Study ◽  
Hollow Fiber Membrane ◽  
Cfd Modeling ◽  
Fiber Membrane ◽  
Wall Shear ◽  
Average Wall Shear Stress

The goal of this study is to develop a computational fluid dynamics (CFD) modeling approach to better estimate the blood flow dynamics in the bundles of the hollow fiber membrane based medical devices (i.e., blood oxygenators, artificial lungs, and hemodialyzers). Three representative types of arrays, square, diagonal, and random with the porosity value of 0.55, were studied. In addition, a 3D array with the same porosity was studied. The flow fields between the individual fibers in these arrays at selected Reynolds numbers (Re) were simulated with CFD modeling. Hemolysis is not significant in the fiber bundles but the platelet activation may be essential. For each type of array, the average wall shear stress is linearly proportional to the Re. For the same Re but different arrays, the average wall shear stress also exhibits a linear dependency on the pressure difference across arrays, while Darcy's law prescribes a power-law relationship, therefore, underestimating the shear stress level. For the same Re, the average wall shear stress of the diagonal array is approximately 3.1, 1.8, and 2.0 times larger than that of the square, random, and 3D arrays, respectively. A coefficient C is suggested to correlate the CFD predicted data with the analytical solution, and C is 1.16, 1.51, and 2.05 for the square, random, and diagonal arrays in this paper, respectively. It is worth noting that C is strongly dependent on the array geometrical properties, whereas it is weakly dependent on the flow field. Additionally, the 3D fiber bundle simulation results show that the three-dimensional effect is not negligible. Specifically, velocity and shear stress distribution can vary significantly along the fiber axial direction.

scholarly journals Analytical Study of Non-Newtonian Reiner–Rivlin Model for Blood flow through Tapered Stenotic Artery

2020 ◽  
Vol 15 (2) ◽  
pp. 295-312
Author(s):  
Nibedita Dash ◽  
Sarita Singh
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Constitutive Relation ◽  
Flow Rate ◽  
Axial Velocity ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Closed Form Solution ◽  
Wall Shear

Stenosis, the abnormal narrowing of artery, significantly affects dynamics of blood flow due to increasing resistance to flow of blood. Velocity of blood flow, arterial pressure distribution, wall shear stress and resistance impedance factors are altered at different degree of stenosis. Prior knowledge of flow parameters such as velocity, flow rate, pressure drop in diseased artery is acknowledged to be crucial for preventive and curative medical intervention. The present paper develops the solution of Navier–Stokes equations for conservation of mass and momentum for axis-symmetric steady state case considering constitutive relation for Reiner–Rivlin fluid. Reiner–Rivlin constitutive relation renders the conservation equations non-linear partial differential equations. Few semi-analytical and numerical solutions are found to be reported in literature but no analytical solution. This has motivated the present research to obtain a closed-form solution considering Reiner–Rivlin constitutive relation. Solution yields an expression for axial velocity, which is utilized to obtain pressure gradient, resistance impedance and wall shear stress by considering volumetric flow rate as initial condition. The effect of viscosity, cross viscosity, flow rate, taper angle of artery and degree of stenosis on axial velocity, resistance impedance and wall shear stress are studied.

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