152
Dynamics
of
the Vascular
System
Many of fluid mechanical simulations and experiments in branching
tubes have taken the assumption of rigid tubes. We have seen in earlier
chapters that blood vessel compliance
is
of
utmost importance in shaping
the pressure and flow waveforms.
Fig.
5.2.5:
Carotid bifurcation model.
A,
8,
C,
D,
E,
F,
S
indicate
flow
corss-section
levels where numerical results are didaved. From Perktold and RaDDitsch
(1995).
One such study that addresses the importance of compliance is that
of
Perktold and Rappitsch
(1995)
who performed computer simulation of
local blood flow and vessel mechanics in a compliant carotid artery
bifurcation model. The
flow
analysis uses the time-dependent, three-
dimensional, incompressible Navier-Stokes equations for non-Newtonian
inelastic fluids. The wall displacement and stress analysis
applies
geometrically nonlinear shell theory where incrementally linear elastic
wall property is assumed. Their comparison of rigid and compliant vessel
models showed that wall shear stress magnitude decreased by
25%
in the
compliant model.
In
general, flow separation results in locally low
