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1. Dr Patrick Geoghegan
Caro 2011 “The Mechanics of Circulation –
2nd Edition” Cambridge Press Chapters 4,
5, 10, 12
FEA/CFD for
Biomedical Engineering
Week 5/6: Biofluid
Mechanics (Arteries)

2. Blood

3. The major roles of the blood include:
• Carries oxygen and nutrients to active tissues
• Delivers carbon dioxide to the lungs
• Brings metabolic end products to kidneys
• Blood is a buffering reservoir that controls pH of biofluids
• Plays a major role in the body's immune system
• In addition to mass, it also transports heat
Blood

4. • It is the liquid component of blood, in which the blood cells
are suspended
• 55% of total blood volume
• Density (ρ) approximately 1030 kg/m3
• With natural proteins the plasma behaves like a
Newtonian fluid with a viscosity of 1.2x10-3 Pa.s.
Blood Plasma

6. Blood Plasma

7. Three Components
• red cells (erythrocytes),
• white cells (leukocytes)
• Platelets
The white cells and platelets play the respective role of
immune response and blood clotting.
The number of white blood cells and platelets are relatively
small compared to the number of red blood cells
Blood Cells

8. • Erythrocytes volume concentration in blood is about 45%.
• This concentration is often referred to as haematocrite
Haematocrite
• Ratio between the volume of red blood cells to the total
blood volume
Blood Cells

9. • The shape of an erythrocyte is biconcave
discoid (shape makes the erythrocytes
flexible to squeeze through small
capillaries below 8μm size
• The density of red blood cells is 1.08x10-3
kg/m3
• The membrane on the outer of a red
blood cell is covered with albumin at
outside and another protein, spectrin,
inside
• The spectrin layer is a skeletal protein
and supports the lipid layer
• The liquid interior is a saturated solution
of haemoglobin
• Haemoglobin binds oxygen and carbon
dioxide
Blood Cells

10. • The erythrocytes aggregate face to face if they are
brought in contact with each other at low shear rates
• Such aggregates are referred to as rouleaux
• The secondary aggregation of the rouleaux leading to a
rouleaux network happens at nearly zero shear rates