  Considerations on implementation of the stress-strain constitutive relations
applied in Computational Fluid dynamics (CFD) simulation of cardiovascular
flows have been addressed extensively in the literature. However, the matter is
yet controversial. The author suggests that the choice of non-Newtonian models
and the consideration of non-Newtonian assumption versus the Newtonian
assumption is very application oriented and cannot be solely dependent on the
vessel size. In the presented work, where a renal disease patient-specific
geometry is used, the non-Newtonian effects manifest insignificant, while the
vessel is considered to be medium to small which, according to the literature,
suggest a strict use of non-Newtonian formulation. The insignificance of the
non-Newtonian effects specially manifests in Wall Shear Stress (WSS) along the
walls of the numerical domain, where the differences between Newtonian
calculated WSS and non-Newtonian calculated WSS is barely visible.
