Characterization of vortex ring in abdominal aortic aneurysm phantom using particle image velocimetry

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KeremTugGokcek_Thesis.pdf

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2021-9

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Gökçek, Kerem Tuğ

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Abdominal aortic aneurysm (AAA) is the permanent enlargement of the abdominal artery that may even rupture at the end, and it is a critical medical situation with a high mortality rate. Although there are some approaches to model its enlargement and rupture, a complete understanding is far from over. A vortex ring is generated during physiological flow pattern, and its evolution should be analyzed in detail to understand its effect on the flow field. The aim of this study is to investigate and characterize vortex rings in a simplified abdominal aortic aneurysm geometry using an experiment setup with Particle Image Velocimetry (PIV) measurement method. An experimental setup is designed and established to simulate physiological flow patterns through a AAA geometry with refractive index match of the phantom and the working fluid. Different vortex identification methods, including λci - criterion, Q - criterion, Δ - criterion and λ2 - criterion have been reviewed and implemented. The vortex structures are characterized for certain phases of different cycles with these methods. A MATLAB code is developed to apply these methods to planar PIV data. The results show that a vortex ring is formed as the instabilities arise, and multi vortex rings can occur simultaneously at certain phases due to collision of this vortex ring with the walls. Furthermore, the mentioned vortex identification methods provided the same results. However, it is seen that they require noise reduction to obtain robust results. A couple of methods are tested for this purpose. Further studies are required to reveal more about the vortex mechanics.

Subject Keywords

Abdominal aortic aneurysm, Vortex identification, Hemodynamics, Particle Image Velocimetry

URI

https://hdl.handle.net/11511/92149

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

K. T. Gökçek, “Characterization of vortex ring in abdominal aortic aneurysm phantom using particle image velocimetry,” M.S. - Master of Science, Middle East Technical University, 2021.