Abstract
Anatomic aortic anomalies are seen in many medical conditions and are known to cause disturbances in blood flow. Turner syndrome (TS) is a genetic disorder occurring only in females where cardiovascular anomalies, particularly of the aorta, are frequently encountered. In this study, numerical simulations are applied to investigate the flow characteristics in four TS patient- related aortic arches (a normal geometry, dilatation, coarctation and elongation of the transverse aorta). The Quemada viscosity model was applied to account for the non-Newtonian behavior of blood. The blood is treated as a mixture consisting of water and red blood cells (RBC) where the RBCs are modeled as a convected scalar. The results show clear geometry effects where the flow structures and RBC distribution are significantly different between the aortas. Transitional flow is observed as a jet is formed due to a constriction in the descending aorta for the coarctation case. RBC dilution is found to vary between the aortas, influencing the WSS. Moreover, the local variations in RBC volume fraction may induce large viscosity variations, stressing the importance of accounting for the non-Newtonian effects.
Highlights
The circulatory system distributes oxygenated blood and nutrients to all parts of the body
Changes in anatomy can result in abnormal blood flow pattern, which may lead to alteration of the forces acting on the vessel wall
The results show the distribution of red blood cells (RBC) in the aorta significantly differs between the four investigated geometries
Summary
The circulatory system distributes oxygenated blood and nutrients to all parts of the body. The oscillatory shear index and relative residence time may appear at locations that are at low risk of developing atherosclerosis (Wyk et al 2014) All these studies consider blood as a continuum where the bulk properties of the fluid have been set by either assuming a Newtonian fluid or applying a non-Newtonian viscosity model. Arterial flows are subject to relatively high amplitude perturbations of different scales as the blood passes through the left ventricle of the heart, the aortic valve and the aortic root With such strong perturbations, transition to turbulence would be much faster than in a pipe under laboratory conditions. A fully turbulent flow is not observed for any of the four geometries investigated
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