Vascular Branching
151
studies.
Li
(1
985) has found that alteration of pressure and flow through
vascular junctions is more significantly
affected
by
geometry
than
by
elastic
factors.
The importance of area ratios is dealt in the next section. Area ratios
and curvatures of flow divider and lateral junctions are major geometric
parameters considered in the formulation of many fluid mechanical
studies. Li (1985) has found that alteration of pressure and flow through
vascular junctions is more significantly affected by geometry than by
elastic factors.
The effect of flow divider curvature was studied in a numerical
simulation model by Friedman and Ehrlich
(1
984).
Two-dimensional
steady
flow
calculation in computational regions
obtained
from
radiographs of human aortic bifurcations have been shown to correlate
well with unsteady measurements of wall shear in flow-through casts of
the same vessels. Their results suggest that wall slope, hence curvature is
an important factor affecting shear that contributes to atherogenesis. This
approach is shown
in
Figs. 5.2.3 and 5.2.4.
0.8
-
-
-
Straight
mlls
-
Actual
walls
8
0
iiI
----
I
I
2
X
(cml
-0.1
8
1
Fig.
5.2.4:
Slope profile along the actual and straight inner walls. Since the end points
of
the straight walls are the same as those
of
the corresponding actual walls, the slopes
of
the straightened walls are equal to the mean slopes of the actual walls. From Friedman
and Ehrlich
(1984).
