ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

compared by overlaying the real data to drawn stent.
2.2. Mesh Generation and Boundary Condition and Post Processing
CFD analysis were conducted using AcuSolve FE-Based CFD Solver (AcuSim Inc/
Altair Inc., USA) . Transient boundary conditions were applied on both the inlet and
outlet similar to [6]. Inlet boundary conditions was taken as the time varying nodal
velocity profile as to Womersley Flow assumption before the inlet, given as
u
n
x, t
C
0
Re
k
max
k1
J0
1
Ck
J
2 2
1
3
ki
3/
2 ki
x
3/
2
0ki
3/
2
J1ki
3/
2
J i where n u stands for the normal velocity at the inlet of the model, C k are constants
(such that Ck Ak
iBk
), 0 J and J 1 are Bessel functions of First Type order 0 and 1, k
is the harmonic count in Fourier series,
/ 2
0
k
e
i
kt
k R k
is the Womersley index, is
density, is the infinite-shear-rate viscosity, R is average radius of the inflow cross
section, is the heart rate in radians per second (here, 2 rad/s) and x is the
dimensionless distance from center of inflow.
Patient 1 Patient 2 Patient 3 Patient 4
Fig. 2 - The Views of Generated 3D CAD Models used For Unstented Analysis
The Womersley index for the fundamental frequency is 3.2 for this study. The outlet
boundary condition was time-varying pressure, given in the series-form
kmax
ikt
Pout
t P0
Re
Pk
e as in [6]. No slip wall conditions were applied where the
k 1
blood met any solid structure – either the arterial wall or the stent wire. Carreau type
nonlinear viscosity model was applied for the blood, parameters as in [7].
Implicit time integration was applied with 200 steps per cardiac cycle (assumed to be
1Hz). The meshing procedure was completed within HyperMesh Preprocessing
Software (Altair Inc., USA) and then exported to AcuSolve for running. All meshes
were tetrahedron elements with a finer resolution of the boundary layer. Each model
solved on 48-core; 128GB RAM HP DL 585G7 servers on approximately 120hr of wall
time per model with MPI parallelization. Transient velocity and pressure data for the
whole model were transferred into EnSight Software for Post-Processing (CEI Inc). The
data from the initial cardiac cycle was disregarded, and the remaining was used as to
common practice in transient FE analysis to avoid appearing transients due to