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Patient Specific Modelling of Blood Flow in Coronary Artery
Keywords: Coronary artery, Stenosis, Wall shear stress, Flow rate - Pressure relation, Fractional Flow Reserve.
In many patients, the performance of heart is considerably affected by the blocks occurring in coronary arteries because of plaque formation. The plaques formed inside an artery forces the heart to work harder to nourish the oxygenated blood to vessels and the heart muscles. This study investigates the flow rate vs pressure relation in stenosed coronary arteries via numerical modelling by using ANSYS FLUENT software. In order to maintain accuracy, the Transition Shear Stress transport (SST) k-ω turbulence model is used to record the changeover stage from laminar to turbulent flow and vice versa. In this study, three patient cases with different stenosis (block) levels (i.e., block level 33%, 66% & 85%) are analysed by considering blood as a non-Newtonian fluid, and blood flow as pulsatile in nature. All the three cases are asymmetric stenosis. The results show very high Wall Shear Stress (WSS) along the stenosis. The pressure is found to be decreased immediately after the stenosis. The study reveals that the pressure drop can be correlated to the flow rate at different stenosis level. Pressure drop becomes more significant at severe degrees of stenosis (66% and 85%) compared to the mild case (33%). All the cases with different stenotic levels are also analysed at hyperaemic conditions and found that even at 45% stenosis, the case can go near to critical. The severity of vessel constriction can be estimated by comparing the simulated pressure drop before and after the stenosis and WSS, with the ones for a healthy artery. The study throws light towards the distribution of shear stress and pressure drop along the artery wall, which are considered as indicators of the commencement of heart disease and further growth of stenosis. Computed Fractional Flow Reserve (FFR), which relates to % stenosis vs the pressure variations, can be used as an index to diagnose the severity of stenosis. In the present study a methodology have developed to calculate the FFR value for unknown percentage stenosis based on the simulated results obtained from 33%, 66% and 85% stenosis. Thus, criticality of a patient with certain percentage stenosis can also be evaluated. This estimate can be recommended as a non-invasive diagnostic tool for the early detection of atherosclerosis.

Journal of Applied Fluid Mechanics

The Journal of Applied Fluid Mechanics (JAFM) is an international, peer-reviewed journal which covers a wide range of theoretical, numerical and experimental aspects in fluid mechanics. The emphasis is on the applications in different engineering fields rather than on pure mathematical or physical aspects in fluid mechanics. Although many high quality journals pertaining to different aspects of fluid mechanics presently exist, research in the field is rapidly escalating.