Am J Physiol Heart Circ Physiol. 2026 Jun 2. doi: 10.1152/ajpheart.00016.2026. Online ahead of print.
ABSTRACT
The assumption that blood adheres to vessel walls with zero tangential velocity component, the so-called "no-slip" boundary condition, is a foundational premise of cardiovascular fluid dynamics. Whether the no-slip condition holds in vivo, however, remains unknown. Seven healthy adult volunteers underwent cardiovascular magnetic resonance imaging. Using 4-dimensional flow magnetic resonance imaging of the descending thoracic aorta and modeling blood as a Navier-Stokes fluid, near-wall blood velocities were quantified, and wall shear stress was calculated based on the measured velocity fields. Within the Navier-Stokes data-assimilation framework, tangential wall velocities of approximately 30-80% of the mean luminal velocity were consistently obtained. These results provide evidence for effective macroscopic slip behavior at the aortic wall in vivo. Consequently, wall shear stresses were substantially reduced compared with values obtained under the assumption of no-slip. This finding challenges the universal use of the classical no-slip boundary condition in macroscopic cardiovascular flow modeling and directly affects key blood flow characteristics such as pressure drop, vorticity, wall shear stress, and energy dissipation, which play important roles in both normal and disease-state cardiovascular conditions.
PMID:42228951 | DOI:10.1152/ajpheart.00016.2026