Biomedical Engineering Reference
In-Depth Information
Figure 5.21
Pulsed wave form.
5.4.3
Mechanical Properties
In this study, we deal with relatively large diameters (
d
>
3 mm), the
luid is assumed to be Newtonian.
10
The density and viscosity of the
blood were set to 1050 kg/m
3
and 4.0
×
10
-3
Pa
s.
We set the elastic
modulus to 3.0
MPa and Poisson's ratio is set to 0.45.
5.4.4
Fluid Calculation Method
The governing equations for luid are the Navier-Stokes equations
of incompressible lows and equation of continuity.
u
0
(5.75)
u
u
u
1
2
O
uu
-
p
u
(5.76)
t
S
where
ρ
is the density and
u
is the velocity. In this calculation, we
adopted large eddy simulation (LES) as turbulence model, regarding
that pulsatile unsteady and vortex, separated low within vessels will
occur. To obtain accurate data, subgrid scale of LES is wall-adapting
local eddy viscosity (WALE) model. The WALE subgrid scale model
provides the following mixing-length type formula for the subgrid
scale viscosity:
t
=
ρδ
2
S
w
(5.77)
Search WWH ::
Custom Search