On the Application of Viscoelastic & Viscoplastic Constitutive Relations in the CFD Bio-Fluid Simulations

TL;DR

This paper investigates the impact of viscoelastic and viscoplastic constitutive relations in CFD bio-fluid simulations, finding that non-Newtonian effects are often negligible in certain patient-specific geometries, especially regarding wall shear stress.

Contribution

It provides a comparative analysis of Newtonian versus non-Newtonian models in CFD simulations of cardiovascular flows, highlighting the limited significance of non-Newtonian effects in specific cases.

Findings

Non-Newtonian effects are insignificant in the studied geometry.

Differences in Wall Shear Stress between models are minimal.

Application context influences the choice of constitutive relations.

Abstract

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.