Blood Flow and Thrombus Formation

Abstract

BLOOD RHEOLOGY To analyze blood fl ow and stresses that develop in it, and its interaction with the blood constituents, blood is traditionally considered a continuously deformable continuum in motion. Using this approach, blood can be characterized as a Newtonian fl uid (in which the fl uid deforms linearly as a function of the stress imposed) or a non-Newtonian fl uid (in which the fl uid deforms nonlinearly as a function of the stress). The Newtonian behavior of blood fl ow is relevant to most of the larger arteries in the vasculature. However, blood possesses a unique nonNewtonian viscosity behavior, which becomes apparent when it fl ows through the smaller vessels, such as arterioles and capillaries. This behavior is also observed when blood fl ow forms vortical structures, as may be found in fl ow through cardiovascular prostheses or in cardiovascular disease processes such as stenoses and aneurysms ( 1 ). In analyzing other aspects of hemodynamics such as the apparent reduction of viscosity and the migratory tendency of blood cells in the smaller scale vessels (i.e., the microcirculation), blood may be treated as a suspension of cells in plasma.