Numerical Experiments in Blood Rheology

Whole blood is a concentrated suspension of formed cellular elements that includes red blood cells (RBCs), white blood cells and platelets, representing approximately 46% of the volume in human blood. These cellular elements are suspended in plasma, an aqueous ionic solution of low viscosity. Plasma behaves as a Newtonian fluid but whole blood has non-Newtonian properties. In the large vessels, where shear rates are high enough, it is reasonable to assume that blood has a constant viscosity and a Newtonian behavior. However, in smaller vessels, or in some disease conditions, the presence of the cells induces low shear rate and whole blood exhibits remarkable non-Newtonian characteristics, like shear-thinning viscosity, thixotropy, viscoelasticity and possibly a yield stress. In this talk we discuss some mathematical models well suited to describe blood rheology and present numerical results comparing Newtonian and non-Newtonian simulations of blood flow in several geometries.