Abstract:
This study presents an extensive numerical investigation on the flow phenomena of a blood
analogous fluid through an axisymmetric stenosed artery under both steady and pulsatile flow
conditions. Most of the previous investigations, carried out for this benchmark problem, used
either a simple Newtonian fluid model or a generalized Newtonian (GNF) fluid model like the
power-law or Bingham plastic fluid model to represent the rheological behaviour of blood.
However, many prior rheological studies showed that the real and whole blood exhibits both the
shear-thinning and viscoelastic properties. In this study, for the first time, a multi-mode sPTT
(simplified Phan-Thein-Tanner) model is used to carry out the numerical computation, which
accounts for both the shear-thinning and viscoelastic rheological properties of blood. Additionally, a realistic set of viscoelastic model parameters, obtained by fitting the response of real and
whole blood in standard viscometric flows, is used in this study. An excellent agreement is seen
between the experimentally determined apparent viscosity (in simple shear flows) of blood with
that predicted by the present viscoelastic model and other prior models developed for blood.
Therefore, we believe that this study presents more accurate and realistic numerical results for the
flow of blood through a stenosed artery than that presented by the previous studies in the
literature. A simple Newtonian fluid model is also used in the present analysis to compare and
show how the flow behavior of blood can be influenced by its complex rheological properties
under otherwise identical conditions. We find a significant difference in the flow characteristics
(in terms of the streamline profiles, velocity magnitude, pressure drop, etc.) obtained with the
Newtonian and viscoelastic fluid models. For instance, the velocity gradient is seen to be large
near the artery wall for the viscoelastic fluid model than that seen for the Newtonian model;
whereas, a reverse trend is seen for the pressure drop across the stenosis. Furthermore, we find
that the flow dynamics is strongly modulated by the stenosis geometry, Reynolds number and
flow types, i.e., whether it is steady or pulsatile.
