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.

Numerical simulation of pulsatile blood flow characteristics in multi stenosed coronary artery

2021 ◽  
pp. 1-13
Author(s):  
Sarfaraz Kamangar
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Flow Characteristics ◽  
Stenosis Severity ◽  
Stress Zone ◽  
Wall Shear ◽  
Stenosed Coronary Artery

BACKGROUND: Coronary artery disease (CAD) is reported as one of the most common sources of death all over the world. The presence of stenosis (plaque) in the coronary arteries results in the restriction of blood supply, which leads to myocardial infarction. OBJECTIVE: The aim of this study was to investigate the effect of multi stenosis on hemodynamics parameters in idealized coronary artery models with varying degrees of stenosis and interspace distance between the stenosis. METHODS: A finite volume-based software package (ANSYS CFX 17.2) was employed to model the blood flow. The hemodynamic stenosis parameters of blood, such as the pressure, velocity, and wall shear stress were obtained. RESULTS: The computed results showed that the pressure drop is maximum across the 90% area stenosis (AS). The pressure drop is increased as the distance between the proximal and distal stenosis is decreased across the proximal stenosis for the model P70_D70 durign the systolic period of the cardiac cycle. A recirculation zone is formed behind the stenosis and is restricted by the occurrence of distal stenosis as the interspacing distance decreases, which could lead to further progression of stenosis in the flow-disturbed area. The wall shear stress was found to increase as the distance between the proximal and distal stenosis is increased across the distal stenosis. The maximum wall shear stress was found at the 90% AS. CONCLUSIONS: In the clinical diagnosis an overestimation of distal stenosis severity could be possible. Furthermore, the low wall shear stress zone in between the proximal and distal stenosis may help atherosclerotic growth or merging of adjacent stenosis.

scholarly journals Investigation of blood flow through an artery in the presence of overlapping stenosis

2017 ◽  
Vol 14 (1) ◽  
pp. 39-46 ◽  
Author(s):  
K. Maruthi Prasad ◽  
S. Thulluri ◽  
M. V. Phanikumari
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Couple Stress ◽  
Flow Characteristics ◽  
Couple Stress Fluid ◽  
Flow Equations ◽  
Wall Shear ◽  
Fluid Parameters

The effects of an overlapping stenosis on blood flow characteristics in an artery have been studied. Blood has been represented by a couple stress fluid. The flow equations have been linearised and the expressions for pressure drop, resistance to the flow and wall shear stress have been derived. The results are shown graphically. It is observed that the resistance to the flow, pressure drop and wall shear stress increases with height and length of the stenosis. And it is noticed that the resistance to the flow and pressure drop decreases with couple stress fluid parameters. But wall shear stress increases with couple stress fluid parameters.

Blood Flow Manipulation in the Aorta With Coarctation and Arch Narrowing for Pediatric Subjects

2020 ◽  
Vol 88 (2) ◽  
Author(s):  
Yuxi Jia ◽  
Kumaradevan Punithakumar ◽  
Michelle Noga ◽  
Arman Hemmati
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Aortic Arch ◽  
Flow Direction ◽  
Upper Body ◽  
Patient Specific ◽  
Shear Stresses ◽  
Wall Shear

Abstract The characteristics of blood flow in an abnormal pediatric aorta with an aortic coarctation and aortic arch narrowing are examined using direct numerical simulations and patient-specific boundary conditions. The blood flow simulations of a normal pediatric aorta are used for comparison to identify unique flow features resulting from the aorta geometrical anomalies. Despite flow similarities compared to the flow in normal aortic arch, the flow velocity decreases with an increase in pressure, wall shear stress, and vorticity around both anomalies. The presence of wall shear stresses in the trailing indentation region and aorta coarctation opposing the primary flow direction suggests that there exist recirculation zones in the aorta. The discrepancy in relative flowrates through the top and bottom of the aorta outlets, and the pressure drop across the coarctation, implies a high blood pressure in the upper body and a low blood pressure in the lower body. We propose using flow manipulators prior to the aortic arch and coarctation to lower the wall shear stress, while making the recirculation regions both smaller and weaker. The flow manipulators form a guide to divert and correct blood flow in critical regions of the aorta with anomalies.

Investigation of the Effects of Dynamic Change in Curvature and Torsion on Pulsatile Flow in a Helical Tube

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
N. K. C. Selvarasu ◽  
Danesh K. Tafti
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Secondary Flow ◽  
Pulsatile Flow ◽  
Flow Patterns ◽  
Shear Stresses ◽  
Wall Shear ◽  
Vorticity Flux ◽  
Curvature And Torsion

Cardiovascular diseases are the number one cause of death in the world, making the understanding of hemodynamics and the development of treatment options imperative. The effect of motion of the coronary artery due to the motion of the myocardium is not extensively studied. In this work, we focus our investigation on the localized hemodynamic effects of dynamic changes in curvature and torsion. It is our objective to understand and reveal the mechanism by which changes in curvature and torsion contribute towards the observed wall shear stress distribution. Such adverse hemodynamic conditions could have an effect on circumferential intimal thickening. Three-dimensional spatiotemporally resolved computational fluid dynamics (CFD) simulations of pulsatile flow with moving wall boundaries were carried out for a simplified coronary artery with physiologically relevant flow parameters. A model with stationary walls is used as the baseline control case. In order to study the effect of curvature and torsion variation on local hemodynamics, this baseline model is compared to models where the curvature, torsion, and both curvature and torsion change. The simulations provided detailed information regarding the secondary flow dynamics. The results suggest that changes in curvature and torsion cause critical changes in local hemodynamics, namely, altering the local pressure and velocity gradients and secondary flow patterns. The wall shear stress (WSS) varies by a maximum of 22% when the curvature changes, by 3% when the torsion changes, and by 26% when both the curvature and torsion change. The oscillatory shear stress (OSI) varies by a maximum of 24% when the curvature changes, by 4% when the torsion changes, and by 28% when both the curvature and torsion change. We demonstrate that these changes are attributed to the physical mechanism associating the secondary flow patterns to the production of vorticity (vorticity flux) due to the wall movement. The secondary flow patterns and augmented vorticity flux affect the wall shear stresses. As a result, this work reveals how changes in curvature and torsion act to modify the near wall hemodynamics of arteries.

Fluid-Structure Interaction Analysis on the Effects of Bifurcation Angle Asymmetry in a Left Main Coronary Artery Model

2014 ◽  
Vol 553 ◽  
pp. 316-321
Author(s):  
Ashkan Javadzadegan ◽  
Babak Fakhim ◽  
Rahman T. Nakkas ◽  
Masud Behnia
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Interaction Analysis ◽  
Linear Regression Analysis ◽  
Recirculation Flow ◽  
Bifurcation Angle ◽  
Recirculation Area ◽  
Wall Shear

This study was to investigate the effect of the bifurcation angle asymmetry on recirculation flow, pressure drop and wall shear stress (WSS) in an atherosclerotic model of a left coronary artery with left anterior descending (LAD) and left circumflex (LCX) branches. The linear regression analysis results showed that there is a positive correlation between WSS and bifurcation angle asymmetry. However, small increase in the WSS magnitude due to the increase in bifurcation angle asymmetry revealed the angle asymmetry does not seem to have a profound effect on the WSS. The results also showed that the bifurcation angle asymmetry play a prominent role in determining the pressure drop and recirculation area, while having relatively unnoticeable effects on the wall shear stress (WSS).

scholarly journals Triple-deck and direct numerical simulation analyses of high-speed subsonic flows past a roughness element

2015 ◽  
Vol 774 ◽  
pp. 311-323 ◽  
Author(s):  
G. Mengaldo ◽  
M. Kravtsova ◽  
A. I. Ruban ◽  
S. J. Sherwin
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Direct Numerical Simulation ◽  
Pressure Gradient ◽  
Stokes Equations ◽  
Roughness Element ◽  
Navier Stokes ◽  
Longitudinal Pressure Gradient ◽  
Wall Shear

This paper is concerned with the boundary-layer separation in subsonic and transonic flows caused by a two-dimensional isolated wall roughness. The process of the separation is analysed by means of two approaches: the direct numerical simulation (DNS) of the flow using the Navier–Stokes equations, and the numerical solution of the triple-deck equations. Since the triple-deck theory relies on the assumption that the Reynolds number ($\mathit{Re}$) is large, we performed the Navier–Stokes calculations at $\mathit{Re}=4\times 10^{5}$ based on the distance of the roughness element from the leading edge of the flat plate. This $\mathit{Re}$ is also relevant for aeronautical applications. Two sets of calculation were conducted with the free-stream Mach number $\mathit{Ma}_{\infty }=0.5$ and $\mathit{Ma}_{\infty }=0.87$. We used different roughness element heights, some of which were large enough to cause a well-developed separation region behind the roughness. We found that the two approaches generally compare well with one another in terms of wall shear stress, longitudinal pressure gradient and detachment/reattachment points of the separation bubbles (when present). The main differences were found in proximity to the centre of the roughness element, where the wall shear stress and longitudinal pressure gradient predicted by the triple-deck theory are noticeably different from those predicted by DNS. In addition, DNS predicts slightly longer separation regions.

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.

Computational Modeling of Non-Newtonian Blood Flow Through Stenosed Arteries in the Presence of Magnetic Field

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Aiman Alshare ◽  
Bourhan Tashtoush ◽  
Hossam H. El-Khalil
Keyword(s):  
Magnetic Field ◽  
Blood Flow ◽  
Shear Stress ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Stenosed Artery ◽  
Flow Through ◽  
Wall Shear

Steady flow simulations of blood flow in an axisymmetric stenosed artery, subjected to a static magnetic field, are performed to investigate the influence of artery size, magnetic field strength, and non-Newtonian behavior on artery wall shear stress and pressure drop in the stenosed section. It is found that wall shear stress and pressure drop increase by decreasing artery size, assuming non-Newtonian fluid, and increasing magnetic field strength. In the computations, the shear thinning behavior of blood is accounted for by the Carreau–Yasuda model. Computational results are compared and found to be inline with available experimental data.

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