Biomedical Engineering Reference
In-Depth Information
VELOCITY (m/sec)
TIME 3.000
VELOCITY (m/sec)
TIME 3.213
0.04000
0.4247
0.1625
0.3900
0.1375
0.1125
0.0875
0.3300
0.2700
0.2100
0.0625
0.1500
0.0375
0.0900
0.0125
0.0300
Beginning of the cycle
During acceleration
VELOCITY (m/sec)
TIME 3.311
VELOCITY (m/sec)
TIME 3.481
0.6315
0.4327
0.5600
0.4800
0.4000
0.3200
0.3900
0.3300
0.2700
0.2100
0.2400
0.1500
0.1600
0.0900
0.0800
0.0300
Peak systole
During deceleration
FIGURE 6.3
Temporal variation of the flow patterns within a narrow-necked aneurysm
in the absence of coils. Flow from left to right.
due to lack of experimental data, a Darcy number Da =10 4 was assumed to
represent high resistance. The Darcy number is a measure of fluid resistance
as it flows through the porous matrix. Figure 6.5 shows the flow patterns in
the saccular aneurysm and how they are influenced by the flow in the parent
vessel and by coil embolization. For small values of the Darcy numbers, the
fluid experiences a pronounced large resistance as it flows through the porous
matrix, causing the flow to stop within the aneurysm sac. It can be seen
from this figure that for a Darcy number of 10 4 the narrow-necked aneurysm
sac is less permeable to fluid penetration, and, consequently, the convective
activities within it are suppressed. Our results showed that the blood flow pul-
satility into a side-wall aneurysm was significantly reduced after insertion of a
platinum coil, resulting in a packing density of 20% as depicted in Figure 6.5.
Our results also were consistent with the in vitro findings of Gobin et al. [26].
Search WWH ::




Custom Search