Modeling Blood Flow in Repaired and Healthy Aortic Arches Using Computational Fluid Dynamics

The aortic arch is connected directly to the heart. It is responsible for delivering blood to three arteries, known as head vessels, and the lower extremities. Birth-defects in the aortic arch, known as coarctations (CoA’s), hinder the flow of blood in the body, which can manifest into many health problems. Research was conducted this summer using Computational Fluid Dynamics (CFD) software to analyze flow patterns in healthy and surgically repaired aortic arches, as well as some unrepaired arches to ultimately improve patient outcomes.

Patient MRI and CT scans were provided by the University of Rochester Medical Center, and modeling the flow of blood through the aortic arch was done using the CFD software ANSYS Fluent. The three models used to collect data were the SST k-omega, k-epsilon, and laminar. Patient blood pressure (BP) data was implemented at each of the four major openings in the arch. Some trials used the diastolic BP at the ascending aortic arch, and the systolic BP at the descending aortic arch. The three head vessels were left unassigned so the simulation could calculate pressures at those outlets. Simulations were run to obtain velocity streamlines, pressure contours, and wall shear contours for nine patients.

The SST k-omega model was the most representative. The best residuals were produced using the SST k-omega model and simulation times were efficient (2-3 hours), which corresponds to a smooth model and properly designed mesh. In contrast to the k-epsilon model, the SST k-omega model consistently converged in trials when the k-epsilon model did not. Figures produced by both the SST k-omega model and the laminar model were similar, but additional parameters in the SST k-omega model resulted in more accurate near-wall simulations.

In all, patients with CoA’s displayed more complex velocity streamlines, and greater pressure gradients near the third head vessel on the arch. However, the wall shear in healthy arches compared very closely to those with CoA’s.