Reduced Order Modeling (ROM) of vortex propagation in abdominal aneurysm

Abdominal aortic aneurysm (AAA) is a local dilation of the abdominal aorta. If left untreated, the aneurysm can rupture leading to life-threatening conditions. It has been shown that there exists a vortex ring formation during systole in the AAA, which is confirmed by in-vitro experiments, numerical simulations, and in-vivo measurements. However, the complex interaction between this vortex ring and the endothelial wall poses significant challenges to study it under in-vivo condition. In this study, we perform numerical simulations of blood flow within an idealized AAA to understand the vortex formation and breakdown processes. Our simulation shows the formation of a vortex ring propagating along the length of the aorta during the systole phase of the cardiac cycle. The blood flow velocity profiles are used to supply as inputs for our ROMs. We use both linear (Dynamic Mode Decomposition - DMD) and non-linear (an autoencoder based deep neural network - ADNN) to extract the prominent flow patterns from the simulations. The ROM results show a good correlation between the vortex propagation with the geometrical changes during aneurysm progression.