Numerical analysis of the effect of turbulence transition on the hemodynamic parameters in human coronary arteries

Abstract

Background: Local hemodynamics plays an important role in atherogenesis and the progression of coronary atherosclerosis disease (CAD). The primary biological effect due to blood turbulence is the change in wall shear stress (WSS) on the endothelial cell membrane, while the local oscillatory nature of the blood flow affects the physiological changes in the coronary artery. In coronary arteries, the blood flow Reynolds number ranges from few tens to several hundreds and hence it is generally assumed to be laminar while calculating the WSS calculations. However, the pulsatile blood flow through coronary arteries under stenotic condition could result in transition from laminar to turbulent flow condition.Methods: In the present work, the onset of turbulent transition during pulsatile flow through coronary arteries for varying degree of stenosis (i.e., 0%, 30%, 50% and 70%) is quantitatively analyzed by calculating the turbulent parameters distal to the stenosis. Also, the effect of turbulence transition on hemodynamic parameters such as WSS and oscillatory shear index (OSI) for varying degree of stenosis is quantified. The validated transitional shear stress transport (SST) k-ω model used in the present investigation is the best suited Reynolds averaged Navier-Stokes turbulence model to capture the turbulent transition. The arterial wall is assumed to be rigid and the dynamic curvature effect due to myocardial contraction on the blood flow has been neglected.Results: Our observations shows that for stenosis 50% and above, the WSS avg , WSS max and OSI calculated using turbulence model deviates from laminar by more than 10% and the flow disturbances seems to significantly increase only after 70% stenosis. Our model shows reliability and completely validated.Conclusions: Blood flow through stenosed coronary arteries seems to be turbulent in nature for area stenosis above 70% and the transition to turbulent flow begins from 50% stenosis.

Numerical analysis of the impact of flow rate, heart rate, vessel geometry, and degree of stenosis on coronary hemodynamic indices

“…Nevertheless, critical Reynolds numbers are strongly correlated with the shape and size of the stenosis and the HR [ 13 ]. Recent research demonstrated that the fully turbulent nature of the flow occurs in cases of more than 50% stenosis [ 14 ]. However, our tests performed on the physical models demonstrated that for a 75% stenosis and low Reynolds numbers, the flow velocity profile obtained from a physical stand is the closest to the laminar model.…”

Effect of Stenosis Severity on Wall Shear Stress Based Hemodynamic Descriptors using Multiphase Mixture Theory

“…This model also approaches with an assumption that the blood behaves as a mixture of blood borne particulates and that mixture is considered to be continuum. The present study considers laminar blood flow through a noncompliant artery instead of turbulent flow, as a latest study by Mahalingam et al (Mahalingam et al 2016) showed that in 70% stenosis and above stenosed coronary arteries the blood flow becomes turbulent in nature, whereas, the laminar to turbulent transition of blood flow begins from 50% stenosis.…”

Modeling Blood Pulsatile Turbulent Flow in Stenotic Coronary Arteries

“…Atherosclerosis is the main underlying pathological process of CVDs, and it consists of an inflammatory disorder induced by several unhealthy behaviors and lifestyles, that causes the narrowing of the arteries' lumen [1]. During early stages, there are no significant changes in the flow dynamics, nevertheless, as time progresses, these plaques play a critical role in altering the flow characteristics and transition to turbulence can occur, even at much lower Reynolds number [2], [3]. To understand the flow field changes, several hemodynamic studies have been conducted [4], [5].…”

“…For this reason, computational models have been used as an auxiliary tool for obtaining more reliable results [7]- [9]. In particular, fluidstructure interaction (FSI) [10] and computational fluid dynamics (CFD) [4] have been used as an effective alternative to investigate in detail several blood flow phenomena in blood vessels and an important component in the study of CVDs, allowing the calculation of various hemodynamic parameters with high precision [2], [11], [12].…”

“…Nevertheless, over the past few decades, the investigation into hemodynamics has grown exponentially and researchers have taking different assumptions, because of the blood flow complexity. Some authors assumed the blood flow in coronary arteries to be laminar [4], [14]- [19] and behave as Newtonian fluid [17], [20]- [23]; others studied turbulence transition [2], [3], [24]- [26] and non-Newtonian effects [2], [5], [15], [21], [27]. In fact, in large vessels, blood can be considered as a homogeneous fluid with constant viscosity.…”