Hemodynamics in stenotic vessels of small diameter under steady state conditions: Effect of viscoelasticity and migration of red blood cells.

IF 1 4区医学 Q4 BIOPHYSICS

Biorheology Pub Date : 2015-01-01 DOI:10.3233/BIR-14033

Yannis Dimakopoulos, George Kelesidis, Sophia Tsouka, Georgios C Georgiou, John Tsamopoulos

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引用次数: 29

Abstract

BACKGROUND In microcirculation, the non-Newtonian behavior of blood and the complexity of the microvessel network are responsible for the high flow resistance and the large reduction of the blood pressure. Red blood cell aggregation along with inward radial migration are two significant mechanisms determining the former. Yet, their impact on hemodynamics in non-straight vessels is not well understood. OBJECTIVE In this study, the steady state blood flow in stenotic rigid vessels is examined, employing a sophisticated non-homogeneous constitutive law. The effect of red blood cells migration on the hydrodynamics is quantified and the constitutive model's accuracy is evaluated. METHODS A numerical algorithm based on the two-dimensional mixed finite element method and the EVSS/SUPG technique for a stable discretization of the mass and momentum conservation equations in addition to the constitutive model is employed. RESULTS The numerical simulations show that a cell-depleted layer develops along the vessel wall with an almost constant thickness for slow flow conditions. This causes the reduction of the drag force and the increase of the pressure gradient as the constriction ratio decreases. CONCLUSIONS Viscoelastic effects in blood flow were found to be responsible for steeper decreases of tube and discharge hematocrits as decreasing function of constriction ratio.

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稳态条件下小直径狭窄血管的血流动力学:红细胞粘弹性和迁移的影响。

背景:在微循环中，血液的非牛顿行为和微血管网络的复杂性是高流动阻力和血压大幅降低的原因。红细胞聚集和向内径向迁移是决定前者的两个重要机制。然而，它们对非直血管血流动力学的影响尚不清楚。目的:在本研究中，采用复杂的非均匀本构法检查狭窄刚性血管的稳态血流。定量分析了红细胞迁移对流体力学的影响，并评价了本构模型的准确性。方法:采用基于二维混合有限元法和EVSS/SUPG技术的数值算法，在本构模型的基础上对质量守恒方程和动量守恒方程进行稳定离散。结果:数值模拟结果表明，在慢流条件下，沿血管壁形成了一层厚度几乎恒定的细胞耗尽层。随着收缩比的减小，阻力减小，压力梯度增大。结论:血流中的粘弹性效应是导致管腔和放电红细胞压积以收缩比递减的主要原因。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Biorheology 医学-工程：生物医学

CiteScore

2.00

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： Biorheology is an international interdisciplinary journal that publishes research on the deformation and flow properties of biological systems or materials. It is the aim of the editors and publishers of Biorheology to bring together contributions from those working in various fields of biorheological research from all over the world. A diverse editorial board with broad international representation provides guidance and expertise in wide-ranging applications of rheological methods to biological systems and materials. The scope of papers solicited by Biorheology extends to systems at different levels of organization that have never been studied before, or, if studied previously, have either never been analyzed in terms of their rheological properties or have not been studied from the point of view of the rheological matching between their structural and functional properties. This biorheological approach applies in particular to molecular studies where changes of physical properties and conformation are investigated without reference to how the process actually takes place, how the forces generated are matched to the properties of the structures and environment concerned, proper time scales, or what structures or strength of structures are required.