Quantifying turbulent wall shear stress in a subject specific human aorta using large eddy simulation.

Area of Science:

• Biomedical Engineering
• Computational Fluid Dynamics
• Cardiovascular Science

Background:

• Wall shear stress (WSS) is crucial for endothelial cell function and vascular health.
• Understanding disturbed flow patterns in the aorta is key to identifying disease risks.
• Subject-specific modeling enhances the physiological relevance of hemodynamic simulations.

Purpose of the Study:

• To compute the disturbed flow field and wall shear stress (WSS) in a subject-specific human aorta using large-eddy simulation (LES).
• To decompose WSS into pulsating and fluctuating components for a deeper understanding of its effects on the aortic wall.
• To visualize and identify regions of elevated WSS and oscillatory shear index (OSI) within the aorta.

Main Methods:

• Large-eddy simulation (LES) of blood flow in a subject-specific human aorta.
• Integration of magnetic resonance imaging (MRI) data for accurate geometry and boundary conditions.
• Simulation of 50 cardiac cycles with phase averaging for statistical reliability.
• Introduction of a novel WSS decomposition method into pulsating and fluctuating parts.

Main Results:

• High and oscillating WSS values were predominantly found near aortic arch branches.
• Low and oscillating WSS were observed along the inner curvature of the descending aorta.
• A novel graphical representation of OSI against time-averaged WSS facilitated identification of critical aortic wall locations.

Conclusions:

• The decomposition of WSS provides enhanced understanding of its impact on the aortic wall.
• LES simulations with subject-specific MRI data offer valuable insights into aortic hemodynamics.
• This approach enables both qualitative and quantitative comparisons of WSS patterns in different aortic regions.