Session: 11-13-01: Fluids and Public Health and Medicine / Industrial Flows

Paper Number: 165909

CFD Analysis of Blood Flow in Healthy and Stenosed Human Carotid Artery Under Dynamic Conditions 

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of lipid-laden plaques within the arterial walls, primarily due to elevated low-density lipoprotein (LDL) cholesterol levels in the bloodstream. Over time, these plaques cause narrowing of the arterial lumen, resulting in increased vascular resistance, disturbed blood flow, and localized stiffening of the vessel wall. These hemodynamic changes significantly increase the risk of adverse cardiovascular events, including ischemic stroke. The carotid artery, a critical blood vessel supplying oxygenated blood to the brain, is one of the most commonly affected arteries by atherosclerosis. Progressive stenosis in the carotid artery can impair cerebral perfusion, contributing to ischemic events or plaque rupture. Understanding the detailed hemodynamic effects of varying degrees of stenosis is crucial for improving diagnostic accuracy, risk stratification, and treatment planning. In this study, a computational fluid dynamics (CFD) approach is utilized to numerically simulate pulsatile blood flow in both healthy and stenosed human carotid arteries under generic physiological conditions, using the STAR-CCM+ platform. Three levels of stenosis are considered: mild (<50% lumen reduction), moderate (50–70%), and severe (>70%). The arterial walls are assumed to be rigid, and the flow is treated as steady-state in terms of geometry, which is generically modeled to represent typical carotid artery shapes without precise patient-specific features. A pulsatile inlet boundary condition is applied to replicate the realistic flow behavior induced by the cardiac cycle. The model assumes that the blood behaves as a non-Newtonian fluid to accurately simulate its shear-dependent viscosity, and the k-ω SST turbulence model is used to capture transitional and recirculating flow patterns, particularly in the stenotic regions where flow disturbances are expected to occur. Several key hemodynamic parameters are analyzed to assess the impact of stenosis on blood flow characteristics. These parameters include velocity profiles, pressure distributions, and wall shear stress (WSS). Specific metrics such as Time-Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), and Relative Residence Time (RRT) are also evaluated. Additionally, flow phenomena such as vorticity and helicity are computed to explore local rotational behaviors and the degree of alignment between velocity and vorticity fields. The results indicate that increasing stenosis severity results in higher vorticity, oscillatory shear stress, and longer residence times, which are linked to endothelial dysfunction and an increased likelihood of plaque progression. These findings highlight the importance of CFD simulations in understanding the hemodynamic changes caused by atherosclerotic stenosis. By providing detailed insights into how blood flow is altered by varying degrees of stenosis, this study contributes to the development of non-invasive, patient-specific diagnostic tools and treatment strategies for atherosclerotic disease.

Presenting Author: Carlo Carotenuto University of Modena e Reggio Emilia

Presenting Author Biography: My background is Mechatronic Engineering, with a particular focus on fluid dynamics, biomedical applications and numerical simulation. I graduated from the University of Modena and Reggio Emilia (UNIMORE) in 2021 with a Master's degree in Mechatronic Engineering. My Master's thesis, entitled "Influence of Wall Stiffness on the Fluid Dynamics Behaviour of an Arterial Vessel: A Study of the Carotid Artery", solidified my interest in fluid dynamics, especially as it applies to biomedical research.
Since the beginning of my Master's degree, I have been particularly attracted to the study of fluid dynamics. A first approach to this subject was given to me by the exam "Sistemi idraulici industriali" of Professor M. Milani, where an in-depth study of industrial hydraulic systems was carried out. Then, with my interest fully aroused, I decided to continue with the exams that could give me as many ideas as possible about fluid dynamics. One of the most formative exams was "Simulazione fluidodinamica industriale", taken by Professor C. Forte, where the theoretical concepts learned before were applied thanks to the Computation Fluid-Dynamic three-dimensional numerical simulation using the STAR-CCM + software provided by Siemens.
I had the opportunity to write my Master's thesis at the Hydraulic System Design Research Group under the supervision of Professor M. Milani, author of several publications on numerical simulation with CFD approach and industrial flows. During this period I improved my knowledge of Computational Fluid Dynamics by applying it to the study of blood flow in the carotid artery. In particular, notions of fluid-structure interaction between the plasma and the bio-structure of the heart vessel were implemented to evaluate the velocity and propagation of pressure waves during a whole cardiac cycle.
After graduating, I spent a year as a research assistant, continuing my work in biomedical fluid dynamics. Under Professors Milani and L. Montorsi, I extended my thesis research to analyze the effects of atherosclerosis on arterial blood flow and to model blood-bio interactions in diseased arteries. We also collaborated on a COVID-19 related study analyzing alveolar sac dynamics under SARS-CoV-2 infection, resulting in a published paper: "Computational Fluid Dynamics Study of Particle Deposition on Human Lung Dynamics: A Comparison Between the Healthy and Fibrotic Lung" in the ASME Journal of Engineering and Science in Medical Diagnostics and Therapy.
During this period, I also worked with ALEA Design S.R.L., where I moved into industrial fluid dynamics, working on one-dimensional numerical simulations for hydraulic machines using AMESIM provided by Siemens. This role allowed me to broaden my expertise by developing numerical models for hydraulic systems and testing real industrial applications. This included CFD
simulations of filling machines handling non-Newtonian fluids, a unique and challenging application of fluid dynamics.
I started my Ph.D. in 2022 with a project entitled "Theoretical and Numerical Analysis of Fluid-Dynamic Phenomena for Biomedical Applications". Now in my third year, I have continued my work on modelling blood as a non-Newtonian fluid using the Power-Law model. I also attended the "Computational Tissue Biomechanics" summer school organized by Professor Thomas Christian Gasser of KTH University in Stockholm, which deepened my understanding of tissue biomechanics. My research extended to experimental work where I collaborated with a leading biomedical company to characterize and model hydraulic components in dialysis machines. Using LabVIEW, a National Instruments software, I built a test rig to characterize the hydraulic devices designed for dialysis machines. I then used Amesim to model them using a lumped parameter approach. This work led to a recent publication, "Experimental Analysis of Operating Temperature and Pressure Effects on Aeration in Gear Pumps for Dialysis Machines", which was presented at the 12th Japan Fluid Power Symposium. Currently, I am working on modelling the right carotid artery by CFD and Fluid-Structure Interaction (FSI) using STAR-CCM+. This research considers the arterial wall as a hyperelastic structure and models blood as a strongly non-Newtonian fluid, which has presented unique challenges and opportunities for advanced modelling.

Authors:

Carlo Carotenuto University of Modena e Reggio Emilia
Luca Montorsi University of Modena And Reggio Emilia
Massimo Milani University of Modena and Reggio Emilia