Solution 1.47
(a) By definition, since viscosity varies with strain rate, blood is a nonnewtonian fluid.
(b) Since the apparent viscosity decreases with strain rate, it must be a pseudoplastic fluid, as in
Fig. 1.9(a). The decrease is too slight to call this a “plastic” fluid. (c) These viscosity values are
from six to fifteen times the viscosity of pure water at 37C, which is about 0.00070 kg/m-s. The
viscosity of the liquid part of blood, called plasma, is about 1.8 times that of water. Then there is
a sharp increase of blood viscosity due to hematocrit, which is the percentage, by volume, of red
cells and platelets in the blood. For normal human beings, the hematocrit varies from 40% to
60%, which makes this blood about six times the viscosity of plasma.