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Computational blood flow studies on model and realistic geometries. / Yatishchandra Yatishchandra

Swansea University Author: Yatishchandra Yatishchandra

Abstract

Study of blood flow inside arteries is physiologically significant and computationally challenging. Vascular diseases are the leading causes of death worldwide. Since the geometry is characterized by twisted, bended, bifurcated, trifurcated and multi-branched structure, the numerical modeling of blo...

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Published: 2010
Institution: Swansea University
Degree level: Master of Philosophy
Degree name: M.Phil
URI: https://cronfa.swan.ac.uk/Record/cronfa42411
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Abstract: Study of blood flow inside arteries is physiologically significant and computationally challenging. Vascular diseases are the leading causes of death worldwide. Since the geometry is characterized by twisted, bended, bifurcated, trifurcated and multi-branched structure, the numerical modeling of blood flow is highly complicated. Blood flow is also complex due to the unsteady (pulsatile), three dimensional and helical nature. The computational work in this thesis contains flow simulation of few idealistic models followed by a thorough numerical study of a realistic thoracic abdominal aorta. The three dimensional, viscous Navier Stokes equations are solved explicitly using characteristic based split (CBS) method for time discretization and standard Galerkin method for spatial discretization by imposing physiologically relevant boundary conditions. The artificial compressibility method, which is found to be efficient for biomedical flow problems, has also been discussed briefly. The velocity vectors, wall shear stress contours and pressure distribution plots presented in this thesis provide important insight into actual behavior of blood flow inside arteries. The meshes contain boundary layers for accurate calculation of wall shear stress. The idealistic models studied under steady conditions are straight and s-shaped arteries. All these idealistic models represent healthy arteries. For idealistic models, it is found that complex secondary flow, pressure drop and the WSS vary with change in geometrical configurations and flow rate. In addition to idealistic models, a realistic thoracic aorta with an aneurysm has been studied, by prescribing fully developed pulsatile wave form at the inlet and ail four exits. The patient specific geometrical data of this thoracic aorta has been obtained with the aid of standard CT scans and processed by AMIRA to construct an initial mesh. In this realistic simulation, WSS is found to be low at the beginning of the cardiac cycle, increases to maximum at the peak flow rate and decreases rapidly as the velocity drops. This research work involving fluid dynamical studies in arteries concludes that hemodynamic quantities such as Oscillatory shear index (OSI), flow separation and reversal regions and blood pressure may play a vital role in pathogenesis of arterial anomalies. The Numerical models and the required CBS and velocity profile generation codes have been provided by the team.
Keywords: Bioengineering.;Physiology.
College: Faculty of Science and Engineering

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