Computational Haemodynamics—An Introduction - Computational Hemodynamics: Theory, Modelling and Applications - page 4

(LDL) transportation. By using advanced computer software packages, visualization
of numerical solutions using vectors, contours, or animated movies of unsteady
blood vessel interaction can have a significant impact on delivering solutions. Some
of the aims of this topic are to introduce the reader to current research trends and to
enable the reader to understand to make the right decisions when setting up CHD
models. In particular, new users often encounter incorrect numerically produced
flow results that could be wrongly interpreted as acceptable physical phenomena.
Numerical results obtained must always be thoroughly examined before they are
accepted. Therefore, the new user needs to learn how to properly analyse and judge
the computed results.

1.3 Applications in the Cardiovascular System

1.3.1 CHD as a Research Tool

One of the many uses of CHD is to reveal the physical nature of the interactions
of fluid around and within objects. Fluid is transported through a domain by many
physical processes including dissipation, diffusion, convection, boundary layers
and turbulence. CHD can be employed as a research tool to perform numerical
experiments in order to better understand the physical nature of the fluid dynamics
of blood flow. For example it can be used to better understand blood flow within a
ventricular assist heart device. Fig. 1.3 shows a snapshot in time of the flow through
such a device which reveals the recirculating flow and high wall shear stresses
which can result in thrombosis. This example illustrates how CHD can provide
detailed visualisation to better understand the observed flow structures and some

Fig. 1.3 Three dimensional streamline flow and near-wall velocity profile. Streamline traces of
flow in a ventricular assist device depicting spiralling flow within a ventricular chamber. Swirling
is observed about the centreline of the conical housing. The speed of rotation varies non-linearly
from the housing to the centre of the vortex