Print Email Facebook Twitter CFD Modeling of Abdominal Aortic Aneurysms Title CFD Modeling of Abdominal Aortic Aneurysms Author Van Kruchten, T.J.G. Contributor Poelma, C. (mentor) Westerweel, J. (mentor) Pourquie, M.J.B.M. (mentor) Kalkman, J. (mentor) Faculty Mechanical, Maritime and Materials Engineering Department Process and Energy Programme Fluid Mechanics Date 2015-07-24 Abstract An abdominal aortic aneurysm (AAA) is an excessive localized swelling of the abdominal aortic wall. AAAs are often lethal when they rupture and constitute a significant health risk in the developed countries. CFD simulations can help predict formation, progression, and rupture of AAAs by the use of hemodynamic parameters such as the Oscillatory Shear Index (OSI) that indicates the oscillatory behavior of the wall shear stress vector at the aneurysm wall. Ideally, it is envisioned that the risk of rupture of a particular aneurysm can be estimated by patient-specific parameters that are collected from a patient with minimal effort and to classify the aneurysm into different categories that do or do not pose a considerable risk of rupture. The main objective of this thesis then aims to focus on the underlying flow mechanisms in aneurysm flow and tries to take the first steps towards an abstract aneurysm model by means of a proof of principle regarding the prediction of formation, progression, and rupture locations within an aneurysm, based on simple patient-specific input parameters. To this end, CFD simulations of pulsatile blood flow in an abstract abdominal aortic aneurysm (4A) model are performed for the independent ranges of mean Reynolds number 300?Re m ?1200, Womersley number 15.1 ? ? ? 27.7, aneurysm length ratio 2.6 ? Le ? 5.3, and aneurysm diameter ratio 1.81 ? Di ? 2.55. The effect of the variation of the input parameters on the oscillatory shear index (OSI) is regarded and quantified by the 4A surface-averaged OSI. General trends show that the average OSI decreases 15 percent over the mean Reynolds number range of 300 ? Re ? 1200, increases 16 percent over the Womersley number range of 15.1 ? Wo, ? ? 27.7, increases 11 percent over the aneurysm length ratio range of 2.6 ? Le ? 5.3, and decreases 5 percent over the aneurysm diameter ratio range of 1.81 ? Di ? 2.55, indicating that the mean Reynolds number and the Womersley number have the largest influence on the average OSI for the 4A. The fluctuating wall shear stress vector at the stagnation points of the vortices present in the aneurysm is pointed out as the origin of the high OSI valued axisymmetric rings found on the surface of the 4A. Additionally, there exists an inverse relation between the surface-averaged OSI and the turbulent to periodic kinetic energy ratio, demonstrating the importance of the periodic components. Pulsatile blood flow simulation is also performed on a patient-specific aneurysm geometry and compared with the 4A case with Le = 4.6. The dissimilar flow and OSI results imply that the input parameters alone do not permit to make statements about the OSI values in the patient-specific aneurysm based on the 4A. Subject CFDabdominal aortic aneurysmoscillatory shear indexpulsatile flowwomerlsey number To reference this document use: http://resolver.tudelft.nl/uuid:4e756c07-04c8-464f-9c60-2c4efcab753c Part of collection Student theses Document type master thesis Rights (c) 2015 Van Kruchten, T.J.G. Files PDF MScThesis_CFDModelingOfAA ... uchten.pdf 22.02 MB Close viewer /islandora/object/uuid%3A4e756c07-04c8-464f-9c60-2c4efcab753c/datastream/OBJ/view