184
Dynamics
of
the Vascular System
50
a
cm3/?fo
30
20
10
decrease in p-pe actually leads to a decrease in the flow. When the pulse
wave velocity is
low,
as compared with flow velocity, the latter condition
can occur.
This v/c is known as the velocity fluctuation ratio or
analogous to the Mach number.
Distensibility
of
the elastic tube is given as
1
I
-
:
5-0
cmH20
-
-
-
I
.-
'
I
'.
I
I
I
-
(6.3.8)
6.3.2
Flow
Limitation and Model Experiments
Holt's first such investigation has set the milestone for researchers on
collapsible tube behavior and veins.
His
set-up is shown in Fig.
6.3.1.
Fig.
6.3.1:
(a) Flow in collapsible tube experimental set-up. The upstream and
downstream pressures to the collapsible tube are pl and p2, respectively. The external
pressure
is
denoted
by
pe. (b) Flow
(Q)
as a function
of
downstream pressure (p2),
keeping pe and reservoir head constant. From Holt
(1969).
