Analysis Of Pulsatile Blood Flow Research Articles

Computational analysis of pulsatile blood flow and heat transport dynamics in middle cerebral artery aneurysms in different body physiologies

This paper presents a comprehensive hemodynamic evaluation of two endovascular techniques for treating cerebral aneurysms. Using the finite volume method, we simulated pulsatile blood flow and heat transport dynamics in two saccular aneurysms of varying sizes and shapes. We assessed hemodynamic factors under two coiling conditions with different porosities and deformation stages to identify the most effective treatment for each case. Our computational analysis reveals that stent and coiling applications are more efficient for aneurysms with low-sac volume. Notably, stent placement proves to be more effective than coiling in treating saccular aneurysms. Our findings indicate that stent-induced deformation sufficiently diverts the main blood flow, thereby reducing the risk of aneurysm rupture near the ostium region.

Analysis of pulsatile blood flow through elliptical multi-stenosed inclined artery influenced by body acceleration

The effect of body acceleration on the pulsatile flow of blood through the elliptical artery having stenosis at the multiple positions of its wall is investigated in the current study. The artery is inclined at angle θ with horizontal, and blood is considered as Casson fluid. The mathematical model is processed into non-dimensional form and simplified using assumptions of mild stenosis. The analytical solution of mathematical equations is obtained in the elliptic bounded domain by employing the perturbation technique with Womersley frequency as a perturbation parameter and validated through case comparison with the previous study. The impacts of external acceleration, stenosis height, shape, gravitational acceleration, yield stress, and inclination angle on the flow velocity, flow rate, wall shear stress, and flow resistance are analyzed. It is found that body acceleration, gravitational acceleration, and inclination angle increase the flow rate and diminish the frictional resistance. The more significant yield stress and stenosis height enhance the flow resistance and reduce the flow rate. Moreover, fluid has higher velocity in the case of the non-symmetric shape of stenosis compared with the symmetric form.

Two-phase analysis of blood flow through a stenosed artery with the effects of chemical reaction and radiation

The paper presents a study related to the two-phase analysis of pulsatile blood flow through a narrowed stenosed artery with radiation and the chemical effects. In the model, a vertical artery is considered in which the flow of blood is assumed vertical upward and the direction of an external applied magnetic is in the radial direction of the flow. To understand the behavior of blood flow, graphs of the velocity profile, wall shear stress, flow rate, flow impedance and concentration profile are portrayed with different values of the magnetic and radiation parameters. In order to validate the results, a comparative study is presented between the single-phase and two-phase model of the blood flow, which shows that the two-phase model fits more accurately with the experimental data than the single-phase model, as mean errors are $$0.3\%$$ for the two-phase model while it is $$1\%$$ for single-phase model. For pulsatile flow, the phase difference between the pressure gradient and the flow rate is displayed with the effects of the magnetic field and different heights of the stenosis.

Finite Element Analysis of Pulsatile Blood Flow in Elastic Artery

Finite Element Analysis of Pulsatile Blood Flow in Elastic Artery

Spiral blood flow in aorta–renal bifurcation models

The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta–renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta–renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta–renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries.

Analysis of Pulsatile Blood Flow in a Model of Arterial Aneurysm with Non-Uniform Blood Viscosity

This paper is concerned with the study of pulsatile flow of an incompressible, inhomogeneous fluid in a rigid tube with an aneurysm (used to model an artery). The governing nonlinear equations of motion are written in terms of stream function-vorticity and are solved numerically by a finite-difference technique. The flow quantities relevant to physiological flow are obtained. It is found that the magnitude of wall shear stress increases with increasing values of the fluid viscosity and the pulsatile parameter Strouhal number.

Analysis of Pulsatile Blood Flow in an Elastic Artery Using the Cosserat Continuum Mechanical Approach

A pulsatile flow of micropolar fluid through an elastic vessel with small displacement has been developed to model the blood flow in arteries. For numerical solution of governing equations, the finite difference method has been utilized. Also, by choosing the suitable boundary conditions and using the solution procedures of fluid structure interaction (FSI) problems, the fluid flow simulation has been used in different states, such as rigid or flexible wall and classical or Cosserat theories. We show that our solution in this study is in good agreeable with experimental and analytical results. This article presents the best modeling for blood flow simulation in biomedical jobs with doing stability analysis for numerical code of micropolar fluid flow model and choosing a suitable relaxation factor for receiving to convergence solution.

Fluid-Structure Interaction Analysis of Pulsatile Blood Flow and Heat Transfer in Living Tissues During Thermal Therapy

The current numerical investigation tackles the fluid-structure interaction in a blood vessel subjected to a prescribed heating scheme on tumor tissues under thermal therapy. A pulsating incompressible laminar blood flow was employed to examine its impact on the flow and temperature distribution within the blood vessel. In addition, the arterial wall was modeled using the volume-averaged porous media theory. The motion of a continuous and deformable arterial wall can be described by a continuous displacement field resulting from blood pressure acting on the tissue. Moreover, discretization of the transport equations was achieved using a finite element scheme based on the Galerkin method of weighted residuals. The numerical results were validated by comparing them against documented studies in the literature. Three various heating schemes were considered: constant temperature, constant wall flux, and a step-wise heat flux. The first two uniform schemes were found to exhibit large temperature variation within the tumor, which might affect the surrounding healthy tissues. Meanwhile, larger vessels and flexible arterial wall models render higher variation of the temperature within the treated tumor, owing to the enhanced mixing in the vicinity of the bottom wall.

Three-Dimensional Numerical Analysis of Pulsatile Blood Flow around Different Plaque Shapes in Human Carotid Artery

Three-Dimensional Numerical Analysis of Pulsatile Blood Flow around Different Plaque Shapes in Human Carotid Artery

Large eddy simulation of a stenosed artery

A large eddy simulation is conducted of a 50% stenosed artery. The inlet boundary condition is a physiologically accurate pulsatile flow, representative of that found in a femoral artery. The transient, three dimensional results show the non-axisymmetric nature of the flow field; high values of wall shear stress, oscillatory in both space and time are also observed. The identification of such fluid dynamic quantities within a stenosed vessel is important in understanding the likely causes and ongoing effects on the integrity of the vessel. References S. A. Berger and L-D. Jou. Flows in Stenotic Vessels. Annu. Rev. Fluid Mech. 32:347--382. 2000. doi:10.1146/annurev.fluid.32.1.347 M. Li, J. Beech-Brandt, L. John, P. Hoskins, W. Easson. Numerical Analysis of Pulsatile Blood Flow and Vessel Wall Mechanics in Different Degrees of Stenoses. J. Biomechanics 40:3715--3724. 2007. doi:10.1016/j.jbiomech.2007.06.023 S. S. Varghese and S. H. Frankel. Numerical Modeling of Pulsatile Turbulent Flow in Stenotic Vessels. J. Biomech. Eng. 125 (445--460). 2003. doi:10.1115/1.1589774 S. S. Varghese, S. H. Frankel and P. F. Fischer. Direct numerical simulation of stenotic flows. Part 2. Pulsatile flow. Journal of Fluid Mechanics., 582:281--318. 2007. doi:10.1017/S0022112007005836 B. Xiao and Y. Zhang. Numerical simulation of pulsatile turbulent flow in tapering stenosed arteries. Int. J. Numerical Meth. Heat Fluid Flow, 19(5):561--573. 2009. doi:10.1108/09615530910963526 B. Lieber and D. Giddens. Post-stenotic core flow behavior in pulsatile flow and its effects on wall shear stress. J. Biomech., 23(6):597--605. 1990. doi:10.1016/0021-9290(90)90052-5 M. Paul, Md. M. Molla and G. Roditi. Large eddy simulation of pulsatile blood flow. Medical Engineering and Physics, 31:153--159. 2009. doi:10.1016/j.medengphy.2008.04.014 W. W. Nichol and M. F. O'Rourke. McDonald's Blood Flow in Arteries: Theoretical, Experimental and Clinical Principles, Hodder Arnold, London, 5th edition. 2005. D. N. Ku. Blood flow in arteries. Annu. Rev. Fluid Mech. 29:399--434. 1997. doi:10.1146/annurev.fluid.29.1.399 D. Lilly. A Proposed Modification of the Germano Subgrid-Scale Closure Model. Physics of Fluids, 4:633--635. 1992. doi:10.1063/1.858280 B. Geurts. Elements of direct and large eddy simulation. R. T. Edwards, 2004.

Changes in flow and wall stresses through arterial constrictions offset from the centre of the vessel

Blood flow through small, obstructed vessels is studied by computing flows in tubes featuring three dimensional sinusoidal constrictions. A high order spectral element algorithm determines the extent of physiological flow characteristics such as recirculation zones and wall shear stress (WSS). Comparisons find that an increase in constriction eccentricity gives rise to more intense WSS. Moreover, these irregular flow conditions persist further downstream. Consistently, shear rate increases with Reynolds number and constriction eccentricity. Vorticity perpendicular to the constriction geometry and shear rate both increase with blockage ratio. In axisymmetric geometries, dissipation of the shear layers associated with downstream recirculation occurs more quickly. With larger constriction eccentricities, zones of high WSS are found on the far wall downstream of the constriction. This could lead to degradation of the wall tissue. References Blackburn, H. M. and Sherwin, S. J., Three-dimensional instabilities and transition of steady and pulsatile axisymmetric stenotic flows, J. Fluid Mech., 533, 2005, 297--327. doi:10.1017/S0022112005004271 Blackburn, H. M and Sherwin, S. J., Instability modes and transition of pulsatile stenotic flow: pulse-period dependence, J. Fluid Mech., 573, 2007, 57--88. doi:10.1017/S0022112006003740 Chytilova, E., Malik, J., Kasalova, Z., Dolezalova, R., Stulc, T., and Ceska, R., Lower wall shear rate of the common carotid artery in treated type 2 diabetes mellitus with metabolic syndrome, Accepted for publication in Physiological Research, 2008. http://www.biomed.cas.cz/physiolres/pdf/prepress/1445.pdf Dodds, S. R, The Haemodynamics of Asymmetric Stenoses, Eur. J. Vasc. Endovasc. Surg., 24, 2002, 332--337. doi:10.1053/ejvs.2002.1729 Griffith, M. D., Hourigan, K. and Thompson, M. C., Numerically Modelling Blockage Effects on the Flow between Flat Plates, 15th Australasian Fluid Mechanics Conference, 2004, The University of Sydney, Sydney, Australia. http://www.aeromech.usyd.edu.au/15afmc/proceedings/papers/AFMC00103.pdf Jung, H., Choi, J. W., and Park, C. G., Asymmetric Flows of non-Newtonian Fluids in Symmetric Stenosed Artery, Korea-Australia Rheology J., 16, 2004, 101--108. http://www.rheology.or.kr/down/16-2(6).pdf Karniadakis, G. E., Orszag, S. A. and Israeli, M., High-order splitting methods for the incompressible Navier--Stokes equations, J. Comput. Phys., 97, 1991, 414--443. doi:10.1016/0021-9991(91)90007-8 Karniadakis, G. E. and Sherwin, S. J., 2005, Spectral/hp Element Methods for CFD, 2nd ed., Oxford University Press, Oxford. Li, M. X., Beech-Brandt, J. J., John, L. R., Hopkins, P. R., and Easson, W. J., Numerical analysis of pulsatile blood flow and vessel wall mechanics in different degrees of stenoses, Journal of Biomechanics, 40, 2007, 3715--3724. doi:10.1016/j.jbiomech.2007.06.023 Liu, G. T., Wang, X. J., Ai, B. Q. and Liu, L. G., Numerical study of pulsating flow through a tapered artery with stenosis, Chinese Journal of Physics, 42, 2004, 401--409. http://psroc.phys.ntu.edu.tw/cjp/v42/401.pdf NHS Direct, 2006, Coronary Angioplasty, BMJ Publishing Group Ltd, England and Wales, National Health Service clinical evidence for patients. http://besttreatments.bmj.com/btuk/pdf/18627.pdf Ridker, P. M., On evolutionary biology, inflammation, infection, and the causes of atherosclerosis, Circulation, 105, 2002, 2--4. http://circ.ahajournals.org/cgi/reprint/105/1/2 Ross, R., Cell Biology of Atherosclerosis, Annu. Rev. Physiol., 57, 1995, 791--804. doi:10.1146/annurev.ph.57.030195.004043 Sheard, G. J. and Ryan, K., Pressure-driven flow past spheres moving in a circular tube, J. Fluid Mech., 592, 2007, 233--262. doi:10.1017/S0022112007008543 Thomas, S. M., The current role of catheter angiography, Imaging, 13, 2001, 366--375. http://imaging.birjournals.org/cgi/content/full/13/5/366

Numerical studies of blood flow in healthy, stenosed, and stented carotid arteries

AbstractNumerical analysis of pulsatile blood flow in healthy, stenosed, and stented carotid arteries is performed with the aim of identifying hemodynamic factors in the initiation, growth, and the potential of leading to severe occlusions of a diseased artery. The Immersed Finite Element Method is adopted for this study to conveniently incorporate various geometrical shapes of arteries without remeshing. Our computational results provide detailed quantitative analysis on the blood flow pattern, wall shear stress, particle residence time, and oscillatory shear index. The analysis of these parameters leads to a better understanding of blood clot formation and its localization in a stenosed and a stented carotid artery. A healthy artery is also studied to establish a baseline comparison. This analysis will assist in developing treatments for diseased arteries and novel stent designs to reduce restenosis. Copyright © 2008 John Wiley & Sons, Ltd.

Analysis of pulsatile blood flow in constricted bifurcated arteries with vorticity-stream function approach

This theoretical investigation deals with an analysis of pulsatile blood flow in a model bifurcated artery having a stenosis in the parent arterial lumen. The geometry of the bifurcated arterial segment with an implanted stenosis in the parent duct is given an appropriate mathematical shape with the introduction of suitable curvature at the lateral junction and the flow divider. The vascular wall deformability is duly accounted for although the development of atherosclerosis in the arteries reduces its elastic property to some extent. The streaming blood contained in the bifurcated artery is treated to be Newtonian. The flow dynamic analysis applies two-dimensional unsteady incompressible nonlinear Navier-Stokes equations rewritten in the vorticity-stream function formulation. Following a radial coordinate transformation, these equations are solved numerically by a finite difference scheme with the approximate choice of the inlet and boundary conditions in concert with the biophysical point of view. The final numerical results are highlighted at the end of the paper through the exhibition of the wall shear stress and several time-variant patterns of streamlines and vorticity contours of the flow phenomena, which are highly influenced by the severity of the stenosis and the angle of bifurcation. The applicability of the present model is thus established.

CFD analysis of pulsatile blood flow in an atherosclerotic human artery with eccentric plaques

Atherosclerosis is a slow vascular degeneration. It thickens the internal walls of a blood vessel locally depositing an atherosclerotic plaque. Such reduced lumen increases the resistance to blood flow. Plaques can be punctual (eccentric, here considered) or circumferential (symmetrical). Stenoses do not have a typical shape: we hypothesised here a reference geometry (trapezium) with its possible evolutions (semi-ellipse, triangle). Two criteria (Equivalent Area and Equivalent Dimensions) were then defined to compare the results among the 35 case studies numerically analysed with a Computational Fluid Dynamics code (Comsol Multiphysics 3.3). Blood was considered a Cassonian fluid with modified viscosity equation. The artery was cylindrical, rigid and straight, interested by a pulsatile blood flow. Among the variables: shape and dimensions of the stenoses; number of stenoses (single or coupled pathologies); mutual locations (3 possibilities). The main results were that the length of the consequent flow disturbance is due to the stenotic shape and height; blood flow recirculation, downstream of the pathology, is due to the slope of the stenotic walls; and the peak velocities depend on the shape and height of stenosis. The differences from case to case diminish in diastole.

Shear Stress and Shear-Induced Particle Residence in Stenosed Blood Vessels

Numerical analysis of pulsatile blood flow in stenosed carotid arteries is performed to define hemodynamic factors in the initiation, growth, and potential of leading to severe occlusions of a diseased artery. A fluid-structure interaction algorithm, the immersed finite element method, is used for this study for its convenience in imposing arbitrary stenotic shapes without remeshing. Our computational results provide detailed quantitative analysis on the wall shear stress, shear-induced particle residence time, and oscillatory shear index. The analysis of these parameters leads to a better understanding of blood clot formation and its localization in a stenosed carotid artery. A healthy artery is also studied to establish a baseline comparison.

Numerical Analysis of Pulsatile Blood Flow in a Stented Human Coronary Artery with a Flow Divider

Shear stress is known to play a central role in restenosis formation and is sensitive to stent geometry. Local flow alterations created by a different stents without and with flow divider were studied to compare the hemodynamic effects of Stent design properties on restenosis in stented human coronary artery. Blood pressure and shear stress values were computed in three different sites, including stented arterial segment, pre-stent and post-stent regions using computational fluid dynamics. Blood flow was assumed as pulsatile, incompressible and Newtonian flow. Rigid boundary conditions were assumed for all models. The governing Navier-Stokes equations were solved using commercial software package (Fluent V6.0.12). Stents are assumed with real structure and modeled using the commercial software package (Gambit, V2.0). The arterial wall shear stress distribution was investigated in three major regions and critical sites were located. It is concluded that the wall shear stress between stent struts was sensitive to strut spacing, profile of strut, number of struts and curvature. Our 3D computational fluid dynamics modeling demonstrate that with increasing the angle between two sides of the stent strut the percentage of intrastrut area that exposed to critical value of WSS decreases. By application of a flow divider, the wall shear stress in stented segment increases markedly and so is the pressure gradient in stented segment. Flow divider influences the blood flow pattern in proximal of stented segment. In this section, the WSS increases with application of the flow divider. The results for different diameters of flow divider show that optimum diameter for flow divider is D/3.

Numerical analysis of pulsatile blood flow and vessel wall mechanics in different degrees of stenoses

Hemodynamics factors and biomechanical forces play key roles in atherogenesis, plaque development and final rupture. In this paper, we investigated the flow field and stress field for different degrees of stenoses under physiological conditions. Disease is modelled as axisymmetric cosine shape stenoses with varying diameter reductions of 30%, 50% and 70%, respectively. A simulation model which incorporates fluid–structure interaction, a turbulence model and realistic boundary conditions has been developed. The results show that wall motion is constrained at the throat by 60% for the 30% stenosis and 85% for the 50% stenosis; while for the 70% stenosis, wall motion at the throat is negligible through the whole cycle. Peak velocity at the throat varies from 1.47 m/s in the 30% stenosis to 3.2 m/s in the 70% stenosis against a value of 0.78 m/s in healthy arteries. Peak wall shear stress values greater than 100 Pa were found for ⩾ 50 % stenoses, which in vivo could lead to endothelial stripping. Maximum circumferential stress was found at the shoulders of plaques. The results from this investigation suggest that severe stenoses inhibit wall motion, resulting in higher blood velocities and higher peak wall shear stress, and localization of hoop stress. These factors may contribute to further development and rupture of plaques.

Analysis of pulsatile blood flow in stented human coronary arteries

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Signal Extraction Technology

Signal Extraction Technology

Signal Extraction Technology

Signal Extraction Technology