Case Studies of the Human Cardiovascular System - Computational Hemodynamics: Theory, Modelling and Applications - page 222

2004). The phase contrast images are graphical representations of the velocity com-
ponents (x- and y- directions) maps.

7.5.2.3 CFD Modelling

Creating a CFD mesh of the right atrium chamber and its related vessels are de-
picted in Fig. 7.32 . Here, 3D surfaces were constructed through segmented slices of
the heart chamber. After processing of the geometry, the final output is a tetrahedral
mesh with refinements in the near wall consisted of approximately 800,000 cells.
The blood flow through the right atrium is assumed incompressible, homogeneous,
laminar, and Newtonian. The fluid properties are reported in Table 7.8 . Due to the
unsteady nature of the flow field, a transient CFD simulation was performed. The
range of Reynolds numbers in the atrial flow throughout one cardiac cycle is domi-
nantly laminar while it may be argued that turbulence can be induced through the
curvatures within the geometry. The use of a turbulence model therefore does not
necessarily imply greater accuracy in capturing the flow field. Instead the incorrect
use of a turbulence model, especially models based on fully developed turbulent
flows, will produce an overly diffusive flow because of the additional turbulent
viscosity μ t term. At best, low-Reynolds number turbulence models such as the k-ε
and k-ω provide improvements over their standard versions. However, in order to

Fig. 7.32 Flow chart of CFD modelling for the right atrium

Table 7.8 Fluid properties used in the CFD simulations
Parameter Value Units

Dynamic Viscosity 0.004 Pascal

Density 1176 kgm −3

Range of IVC (Inflow) Velocities − 1.2200 to 40.1450 cms −1

Range of SVC (Inflow) Velocities − 0.5120 to 20.3040 cms −1

Reynolds Number 518-2738