Hemodynamics
of
Large Arteries
129
Brummelen
(1961).
Rewrite Flo in its complex
form
in terms
of
real and
imaginary parts, we have:
Flo
=
X
+jY
(4.5.38)
Womersley obtained an expression for complex wave velocity:
C=
From this, the phase velocity is:
noting again that the Moens-Korteweg wave velocity
is
given by
(4.5.3
9)
(4.5.40)
I
Eh
(4.5.4
1)
The attenuation expressed in terms
of
wavelength
is
given by:
(4.5.42)
-2nz~~xa
ae
=
e
Attenuation represents the degree of damping
of
the propagating pulse.
Womersley later imposed longitudinal constraint of the wall due to
vessel tethering. In the case
of
infinite longitudinal constraint,
C,
wave
velocity takes the
form:
(4.5.43)
When considering the arterial wall as viscoelastic, the above equation is
modified
by
taking into account the viscous property
of
the wall,
