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11.1 INTRODUCTION
The cause and development of many arterial diseases are related to the
flow characteristics of blood and the mechanical behavior of the blood
vessel walls. The abnormal and unnatural growth in the arterial wall thick-
ness at various locations of the cardiovascular system is medically termed
“stenosis.” Its presence in one or more locations restricts the flow of blood
through the lumen of the coronary arteries into the heart leading to cardiac
ischemia. A systematic study on the rheological and hemodynamic prop-
erties of blood and blood flow could play a significant role in the basic
understanding, diagnosis, and treatment of many cardiovascular, cerebro-
vascular, and arterial diseases. It is well known that stenosis (narrowing
in the local lumen in the artery) is responsible for many cardiovascular
diseases. The high blood pressure and the arterial constriction increase
flow velocity and shear stress and decrease pressure substantially leading
to thrombus formation. If this disease takes a severe form, it may lead to
serious circulatory disorders, morbidity, or even fatality. The fact that the
hemodynamic factors play a commendable role in the genesis and growth
of the disease has attracted many researchers to explore modern approach
and sophisticated mathematical models for investigation on flow through
stenotic arteries. In most of the investigations relevant to the domain under
discussion, the Newtonian behavior of blood (single-phase homogeneous
viscous fluid) was accepted. Sankar et al. suggested that this model of
blood is acceptable for high shear rate in case of a flow through narrow
arteries of diameter ≤1,000 μm on the basis of experimental observations
Bernett and White more [1] suggested that blood behaves like a non-New-
tonian fluid under certain conditions. H-B fluid model and Casson fluid
models are used in the theoretical investigation of blood flow through nar-
row arteries. Investigations have mentioned that blood obeys Casson fluid
equation at low shear rates when flowing through a tube of diameter of
0.095 mm or less and represent fairly closely occurring flow of blood in
arteries. In narrow arteries, at a time, the arterial transport becomes much
larger as compared to axial transport, and it contributes to the develop-
ment of atherosclerotic plaques, greatly reducing the capillary diameter.
The problem of flow and diffusion becomes much more difficult through a
capillary with stenosis at some region. The theoretical study of Scott Blair
and Spanner [2] pointed out that blood obeys the Casson's equation only
in the limited range, except at very high and very low shear rate and that
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