Fluid structure interface studies on patient specific abdominal aortic aneurysm geometry
Pwee, Esley Chin Hock
Date of Issue2016
School of Mechanical and Aerospace Engineering
Rupture risk of abdominal aortic aneurysm (AAA) has always been linked to the size of the aneurysms. Currently, the surgical intervention of this condition is still dependent on the size of the aneurysms, where a threshold of 5.5 cm of the maximum diameter of the aneurysms is used. However, there were numerous cases where patients with a small AAA diameter size of less than 5.5 cm, still had their aneurysms ruptured, and eventually passed away. Therefore, many researchers argued that using the maximum diameter was not an accurate way to estimate the rupture risk of the aneurysms. There was an increasing trend of using hemodynamic and computer simulation to analysis the flow behaviour within the aneurysms and predicting the condition of it. In spite of this, there were hardly any two way fluid structural interaction (FSI) simulations done in the research studies that were based on a patient specific AAA geometry model. In this study, the main aim was to create a two way FSI simulation model based on patient specific AAA geometry. Secondary objective was to use the simulation results for two different patient AAA geometry to deduce out a relationship between the rupture risk of AAA and the geometry size. Two way FSI simulation model was created by using ANSYS transient structural, FLUENT and system coupling. Patient specific AAA geometry used in the simulation was created from a 3D reconstruction progress that was established in this study. Boundary conditions of the simulation were extracted out as figures from a reputable research paper. The figures were digitized and rewritten in equations that were coded in the C language so as to be used in FLUENT. The simulation was done based on several assumptions which were the properties of the blood and aorta wall. Results from the simulation indicated that AAA geometry size was not the sole determinant for the rupture risk. There was another factor which may cause the increased rupture risk of the AAA. If both patients used the same boundary conditions, patient with the bigger AAA geometry size would have a lower rupture risk as compared to the patient with a smaller geometry size. Therefore, a patient specified FSI simulation model would be a better tool to determine whether there is a need for surgical intervention.
Final Year Project (FYP)
Nanyang Technological University