Case Studies of the Human Cardiovascular System - Computational Hemodynamics: Theory, Modelling and Applications - page 229

plies for the right pulmonary valves, and thus in C C the RPVs were moved down
and located at the same vertical position as the left pulmonary valves in C A .

7.6.2 Computational Model Setup

The flow simulations were performed using the finite volume method in Ansys
Fluent v13.0 (Ansys Inc.). The diastolic duration was measured at 0.665 s and the
simulation time step size was set to 0.5 ms. The models were meshed with tet-
rahedral elements with an element size determined from grid convergence tests.
Laminar flow was assumed and the blood was modelled as an incompressible,
Newtonian, homogeneous fluid, with a density of ρ = 1050 kg/m 3 and a viscosity of
3.5 × 10 −3 kg/ms, which is a reasonably good approximation for blood flow in large
cavities (Ku 1997). The mass flow rate for each of the four pulmonary vessels was
measured using MR phase mapping scans reported from in vivo studies. For every
vein, a power function was fitted to the diastolic mass flow rate as can be seen in
Fig. 7.36 . The flow pattern is similar for the four pulmonary vessels, but the mass
flow rate differs, where the left superior pulmonary vessel has the lowest inflow
rate.

Fig. 7.36 The power function ( solid line ) was fitted to the mass flow rate measured by MR veloc-
ity phase mapping ( dotted line ). The graphs represent the flow through the LSPV, RSPV, LIPV
and RIPV, respectively