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1

Visco-elastic fluid model in an inclined porous stenosed artery with slip effect and body acceleration

Manisha Rana, Kumar Surendra

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 4

82--104

EN

The present paper analyzes an unsteady magnetohydrodynamic blood flow model of an visco-elastic fluid through an inclined porous stenosed artery with body acceleration and slip effect. Navier-Stokes equations have been used to describe the blood flow model. The governing equation of blood flow is solved by an analytic method by considering blood as an incompressible, visco-elastic fluid, and suspension of RBC’s in plasma. Axial velocity, blood acceleration, flow rate, and shear stress are derived numerically by using the finite Laplace and Hankel transformation and their inverse. The effect of parameters such as the visco-elasticity parameter, Womersley number, Hartmann number, inclination angle, parameter of slip, and body acceleration frequency is analyzed. Axial velocity reduces as the Hartmann number and visco-elasticity parameter enhance and it enhances with the enhancement of the slip parameter and inclination angle. The study is beneficial for finding the effect of slip parameter, porosity factor and Hartmann number when a human body is exposed to MRI and CT scan.

2

Experimental and numerical flow analysis through arteries with stent using particle image velocimetry and computational fluid dynamics method

Tomaszewski Michal, Sybilski Kamil, Baranowski Pawel, Malachowski Jerzy

Biocybernetics and Biomedical Engineering

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2020

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Vol. 40, no. 2

740--751

EN

In the paper, an experimental and numerical flow through various kind of arteries is considered. The flow analyses are carried out on the research set up using Particle Image Velocimetry Method (PIV). The individual components of the research set up are discussed and the measurement methodology is explained. The work consists of two parts. The first one is focused on modelling numerical simulation of the stent installation procedure using an expandable balloon and the flow domain design methodology is described. In the final part, an experimental flow test on an artificial silicone vessel (diameter 3.2 mm) with a stent is performed. The results of the experimental tests are compared with a corresponding numerical simulation. The paper presents numerical simulation for two different flow domains and the results obtained from the experimental tests. In both, the experimental tests and numerical simulation, the pulsatile time dependent flow and pressure characteristic are used. Hemodynamic parameters such as the time average wall shear stress (TAWSS) and velocity vector distribution are analysed. The flow was studied at four Reynolds number values (1223; 2257; 3198; 3762) for the straight vessel and at two values for the vessel containing a stent (1223, 2257). A diameter of the vessel was 3.2 mm. Pulsating blood flow based on the data from the experimental test was analysed. During the numerical simulation it was verified which regions of the vessel had TAWSS values below 0.4 Pa. A satisfactory correlation between outcomes of the numerical simulation and the experimental test was obtained. The flow analysis is conducted in ANSYS Fluent software. Additionally, the methodology for defining the velocity profile at the entrance is presented, in order to form the velocity profile in the first step of analysed cases. The study shows possibility to create a new research set up capable of testing various clinical cases of varying pressure values in the setup, or testing the effects of vessel geometrical changes, which allows observing an influence of those parameters on the fluid flow characteristic. As the analysis for the stent has shown, the regions of low TAWSS values are located in a close proximity to the stent struts.

3

Numerical and experimental analysis of balloon angioplasty impact on flow hemodynamics improvement

Tomaszewski Michał, Sybilski Kamil, Małachowski Jerzy, Wolański Wojciech, Buszman Piotr P.

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 3

169--183

EN

Purpose: The paper focuses on the numerical and experimental evaluation of the fluid flow inside chosen fragments of blood vessels. In the first stage of the study, the experimental tests were conducted using a research test stand, designed to be used in this evaluation. The study evaluated the blood flow through a silicone vessel with an implanted coronary stent. Methods: The PIV method was used in order to visualize the flow vectors inside a silicone vessel. Deformed vessel geometry implemented for computational fluid dynamics purposes was obtained owing to a non-linear simulation of the stent expansion (angioplasty process) in a silicone vessel. Additionally, a vessel model with a statistical 55% area stenosis and an irregular real vessel with an atherosclerotic plaque were also subjected to analysis from the hemodynamic flow point of view. A vessel with a statistical stenosis was also used to simulate the angioplasty process, which resulted in obtaining a flow domain for the vessel with an atherosclerotic plaque after the stent implantation. Results: For each case, distributions of parameters such as OSI or TAWSS were also analyzed and discussed. The areas of low TAWSS values appear close to the stent struts. Conclusions: Stents with increased diameters, compared to the normal vessel diameter, create a higher risk of occurrence of the areas with low WSS values. Excessive stent deformation can cause inflammation by injuring the vessel and can initiate the restenosis and thrombotic phenomena through the increased vessel diameter.

4

Mechanical guidelines on the properties of human healthy arteries in the design and fabrication of vascular grafts: experimental tests and quasi-linear viscoelastic model

Faturechi Rahim, Hashemi Ata, Abolfathi Nabiollah, Solouk Atefeh

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 3

13--21

EN

Knowledge of mechanical behavior of healthy human arteries as the guidelines to target properties of vascular grafts deserves special attention. There is a lack of mathematical model to characterize mechanical behavior of biomaterial while many mathematical models to reflect mechanics of human arteries have been proposed. The objective of this paper was set to measure mechanical properties of healthy human arteries including Common Carotid Artery (CCA), Abdominal Aorta Artery (AAA), Subclavian Artery (SA), Common Iliac Artery (CIA) and Right and Left Iliac Artery (RIA and LIA) and compare them to those of commercial ePTFE and Dacron®. Methods: Series of stress relaxation and strain to failure tests vere performed on all samples. The experimental data was utilized to develop quasi-linear viscoelastic (QLV) model of both natural and artificial arteries. Results: ePTFE is the stiffest sample, while the CCA is the most compliant one among all. RIA and CIA are more viscous than the other natural arteries, while AA and CCA are less viscous. The proposed model demonstrated an accurate fit to the experimental results, a proof of its ability to model both nonlinear elasticity and viscoelasticity of the human arteries and commercial ones. Conclusions: ePTFE and Dacron® are much stiffer than human arteries that may lead to the disruption of blood hemodynamic and may not be biomechanically feasible as a replacement.

5

Reversed Robin Hood syndrome in the light of nonlinear model of cerebral circulation

Piechna A., Cieslicki K.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 2

459--464

EN

The brain is supplied by the internal carotid and vertebro-basilar systems of vessels interconnected by arterial anastomoses and forming at the base of the brain a structure called the Circle of Willis (CoW). An active intrinsic ability of cerebral vascular bed maintains constant Cerebral Blood Flow (CBF) in a certain range of systemic pressure changes. This ability is called autoregulation and together with the redundant structure of the CoW guarantee maintaining CBF even in partial occlusion of supplying arteries. However, there are some situations when the combination of those two mechanisms causes an opposite effect called the Reversed Robin Hood Syndrome (RRHS). In this work we proposed a model of the CoW with autoregulation mechanism and investigated a RRHS which may occur in the case of Internal Carotid Artery (ICA) stenosis combined with hypercapnia. We showed and analyzed the mechanism of stealing the blood by the contralateral side of the brain. Our results were qualitatively compared with the clinical reports available in the literature.

6

Modelowanie przepływu krwi w naczyniach krwionośnych miażdżycowo zmienionych

Mordal K., Szarek A.

Aktualne Problemy Biomechaniki

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2017

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z. 13

49--56

PL

Artykuł poświęcono modelowaniu przepływów krwi w tętnicach zdrowych i zwężonych w wyniku miażdżycy przy różnych wysokościach powstałych przewężeń. Część wstępna obejmuje kwestie dotyczące układu krwionośnego, krwi i chorób układu krążenia (miażdżycy). W części badawczej zaprezentowano zagadnienia dotyczące przygotowania modeli fizycznych tętnic oraz wyniki symulacji przepływu krwi. Przeprowadzone badania pozwoliły określić, jaki wpływ na prędkość przepływu, rozkład ciśnienia ma stopień zaawansowania miażdżycy.

EN

This article is about modelling of blood flow in healthy arteries and narrowed as a result of a atherosclerosis at different stages of its development. A preliminary section covers issues concerning cardiovascular system, blood and cardiovascular diseases (atherosclerosis and hypertension). The research presents issues related to physical models of arteries and blood flow simulations. Conducted examinations allowed to determine the effect of the severity of atherosclerosis on flow velocity and pressure distribution.

7

A mathematical model for blood flow through straight artery of slightly non-circular cross-section

Poria S., Dey K. N., Mazumdar H. P.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 1

261-275

EN

In this paper, a model is presented for investigating some hydrodynamic characteristics of blood flow through a large arterial vessel of slightly non-circular cross section. The viscosity of blood is assumed non-uniform due to a distribution of erythrocytes (red cells). The effects of such variation of viscosity on the hydrodynamic flow characteristics, e.g., velocity profiles, volumetric flow rate and shear stress distribution are investigated. These characteristics are then compared with the similar results obtained for the case of blood flow through the corresponding tube of circular cross section.

8

Complex analysis of rupture risk of intracranial saccular aneurysms upon hemodynamic and geometric parameters

Szafrański K.

Biocybernetics and Biomedical Engineering

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2009

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Vol. 29, no. 1

43-59

EN

The paper includes a new concept of assessment of rupture risk of intracranial saccular aneurysms using geometric and hemodynamic parameters of aneurysm, artery and blood. Previous decision systems are mainly based on the size of aneurysm and frequency of subarrachnoid hemorrhages, therefore after performing simulation tests it has been proved that the complex assessment of clinical cases is possible thanks to evaluation of shape and size coefficient of a secondary aneurysm occurring on the surface of a primary aneurysm, width of a primary aneurysm neck, curvature of an artery on which a primary aneurysm is located and the size of blood impingement area at artery wall. The paper contains results of the simulation tests of blood flow in the primary and secondary aneurysm, as well as verification of proposed criteria of rupture risk assessment for 5 clinical cases.