Numerical demonstration of Dean-type secondary flows in the human aorta, corroborated by clinical data

The human aortic arch is a system that is being organized by curvature–inertia coupling into cross-sectional flow that is organized into Dean-type vortices whose strength can be quantified using the Dean number. The current research re-formulated patient-specific arches based on contrast-enhanced computed tomography angiography and established four centerline-orthogonal planes of analysis between the distal ascending and proximal descending segments. Planes A and B are in the distal ascending part; Plane C is close to the apex of the arch, and Plane D is in the proximal descending aorta above the isthmus. Magnetic resonance imaging was used to get inflow waveforms/branch splits and through-plane velocities that were compared. Near-wall resolved, physiology-based computational fluid dynamics (Newtonian blood; unsteady Reynolds averaged Navier–Stokes shear stress transport; y+<1; Time scale: Δt≈T/100–T/200 with Courant number ≲1) was solved under primarily elastic walls with a limited two-way fluid–structure interaction (FSI) sensitivity check. We plotted a secondary-flow intensity (SFI) index vs Dean number (De) with an incipient and sustained threshold of 0.2 and 0.5. All the planes were lying on the shoulder-to-plateau of SFI(De) at peak systole; Plane C was resting on the plateau (SFI ≈ 1), which implies well-organized Dean cells, whereas the A–B planes exhibited strong and slightly weaker vortices. The early diastole rotated every plane to the left side of SFI(De), stratifying secondary flow (A in the transitional knee; C–D on the shoulder) and turning the axial pressure gradient around, with recirculation near branches. Shear measurements were in published envelopes, which facilitated numerical strength. The De lens clinically connects anatomy and hemodynamics to points susceptible to oscillatory shear, allowing plans to be made with curvature awareness, risks to be assessed in branch-specific ways, and longitudinal follow-up to be performed by monitoring the location of a patient on SFI(De).