Key result
Non-Newtonian blood models alter large artery WSS estimates but match Newtonian models in cerebral vasculature.
Why the study?
It remains unclear whether and under what conditions blood can be simplified to a Newtonian fluid in computational fluid dynamics analyses, with contradictory results reported across studies.
In computational fluid dynamics, blood should be modelled as a non-Newtonian fluid for large arteries to accurately estimate wall shear stress, while a Newtonian assumption is sufficient for cerebral vasculature.
Non-Newtonian models may refine large-artery WSS estimates; leaves open standardization for cerebral CFD simulations.
Results obtained with computational fluid dynamics (CFD) rely on assumptions made during a pre-processing stage, including a mathematical description of a fluid rheology. Up to this date there is no clear answer to several aspects, mainly related to the question of whether and under what conditions blood can be simplified to a Newtonian fluid during CFD analyses. Different research groups present contradictory results, leaving the question unanswered. Therefore, the objective of this research was to perform steady-state and pulsatile blood flow simulations using eight different rheological models in geometries of varying complexity. A qualitative comparison of shear- and viscosity-related parameters showed no meaningful discrepancies, but a quantitative analysis revealed significant differences, especially in the magnitudes of wall shear stress (WSS) and its gradient (WSSG). We suggest that for the large arteries blood should be modelled as a non-Newtonian fluid, whereas for the cerebral vasculature the assumption of blood as a simple Newtonian fluid can be treated as a valid simplification.
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Tyfa et al. (2023) studied Blood flow haemodynamics (n=3). Non-Newtonian blood rheology models vs. Newtonian fluid model was evaluated on Wall shear stress (WSS) and its spatial gradient (WSSG). Non-Newtonian blood rheology models produced significant quantitative differences in wall shear stress and its gradient compared to Newtonian models in large arteries, whereas the Newtonian assumption was a valid simplification for cerebral vasculature.
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