Relative residence time and oscillatory shear index of non-Newtonian flow models in aorta

Abstract

Four molecular Non-Newtonian viscosity models plus the Newtonian one were analyzed for the normal human aorta under oscillating flow via: molecular viscosity, time Average Wall Shear Stress (AWSS), Oscillatory Shear Index (OSI) and Relative Residence Time (RRT). The capabilities of the applied non-Newtonian law models appear at low strain rates. The Newtonian blood flow treatment is considered to be a good approximation at mid-and high-strain rates. All blood flow models yield a consistent aorta pattern. High RRT values develop in the concave part of the aortic arch downstream to left subclavian artery. In this region the molecular viscosity is elevated, the WSS is low and the OSI is high. Concave aorta parts are prone to exhibit elevated RRT. The non-Newtonian Power Law blood flow model approximates the molecular viscosity, WSS, OSI and particularly the RRT in a more satisfactory way. High RRT distribution is emerging as an appropriate tool for identifying the possible regions of atheromatic concentrations.