TEVP model predictions of the pulsatile blood flow in 3D aneurysmal geometries

In recent years, significant progress in hemorheological modeling has occurred after the development of constitutive models able to represent the major physical mechanisms that govern the interaction, deformation, and motion of blood cells and plasma. Only a few of them have a tensorial form and can be applied in complex multidimensional flows, allowing a better understanding of hemodynamics and the evolution of biological processes in tissues. In this research, the pulsatile blood flow in 3D rigid aneurysmal geometries is studied in silico, employing our integrated elasto-viscoplastic constitutive model with thixotropy (TEVP), the parameters of which have been evaluated for normal blood subjects. Blood flow is investigated under sinusoidal waveforms with different frequencies and amplitudes, providing a thorough parametric study. As pulse frequency increases, the variation of the structure parameter decreases, and a recirculation is formed inside the aneurysmal dome. Moreover, a significantly higher value of the wall shear stress (WSS) develops around the mouth of the aneurysm, potentially leading to a progressive increase in the size of a real sack. Interestingly, WSS exhibits spatial oscil-lations and attains higher amplitudes along the part of the tube wall beside the aneurysm, where an instability is developed. With an increase in the pulse amplitude, blood gets softer and flows more easily. At the same time, the WSS inside the aneurysm remains low enough to potentially promote a growth or rupture, since low wall-stresses have been related to these processes. The curvature of the parent vessel of the aneurysm affects the flow dy-namics throughout the cycle. In contrast to the WSS, the magnitude of the total stress for the curved vessel is higher than that for the straight vessel.

Automated summary

In recent years, significant progress has been made in hemorheological modeling with the development of constitutive models that can represent the physical mechanisms of blood cell and plasma interaction. This study focuses on pulsatile blood flow in 3D rigid aneurysmal geometries to better understand hemodynamics and biological processes. The results show that pulse frequency affects the flow structure, leading to recirculation in the aneurysmal dome. Increased pulse amplitude makes blood flow more easily, but with low wall shear stress inside the aneurysm, which may contribute to growth or rupture. The curvature of the parent vessel affects the flow dynamics, with higher total stress compared to straight vessels.