Page 19, hemodynamics, Dr. D. Penney
A Newtonian fluid is one in which the flow is proportional to the perfusion pressure. Even when blood is flowing through rigid tubes, the flow rate is still not proportional to the perfusion pressure, at least over some range of pressure and flow. This is because the viscosity is dependent on the radius. A Newtonian fluid is also one in which viscosity is independent of the radius. This of course is true for water. For blood, however, when the tube radius decreases below about 1 mm, the viscosity sharply decreases. More about this below.
BACK TO INDEX