Numerical analysis of multistenosed multiphase patient’s specific left coronary artery subjected to fluid structure interaction / Abdulgaphur Athani

Abdulgaphur , Athani (2022) Numerical analysis of multistenosed multiphase patient’s specific left coronary artery subjected to fluid structure interaction / Abdulgaphur Athani. PhD thesis, Universiti Malaya.

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Abstract

The cardiovascular diseases (CVD’s) constitute a primary cause of morbidity and mortality. Atherosclerosis, often known as plaque, is a chronic inflammatory condition characterized by changes in arterial tissues that last a lifetime. Blood elements deposit and alter due to plaque ruptures, resulting in acute myocardial infarction. This research contributes to the influence of multiphase blood flow in multi-stenosed Left Coronary Artery (LCA) to reduce CVD’s. Initially, 3D ideal artery models were developed for Computational Fluid Dynamics (CFD) and Fluid Structure Interaction (FSI) investigations with varying percentile of stenosis. Furthermore, the research has been expanded to include patient’s specific CT scan data to analyse the hemodynamic parameters with combining CFD and Medical Image Processing software, with a focus on the coronary artery wall for deformations. For the first time, a computational study of multi-phase blood flow via multiple stenosis in LCA (both ideal and patient’s data) was carried using the multiphase mixture theory model. In these instances, the plasma is modelled as a continuous liquid phase and the Red Blood Cells (RBCs) are modelled as a dispersed phase, with the Carreau non-Newtonian viscosity model being used to investigate the RBCs macroscopic behavior in three different degrees of multiple-stenosis (MDOS) geometries, namely 70-70, 80-80, and 90-90 percentile. FSI results reveal that, the degree of stenosis has a significant impact on stress values, leading to high deformation and high Von-Mises stresses. Furthermore, the main findings of the study demonstrated that, the number of stenosis influences the shear stress regions and increases the stress levels with increase of stenosis percentages. However, the recirculation zone found to be greater for multiphase analysis compared to single phase blood flow due to presence of drag forces between two phases. Hence, it concludes that, the atherosclerosis is a disease of the artery wall that develops in vulnerable areas due its blood coagulation and wall effects which later cause of the CVDs. Entirely, the described multiphase blood flow through multiple stenosis arteries with presence of endothelium wall for different degrees of multi-stenosis (MDOS) severity indices with imaging modalities enables the health professionals to diagnose the CVD’s more accurately and to treat the disease before it becomes fatal.

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