A theoretical model for the Fåhræus effect in medium–large microvessels.

This paper presents a mathematical model capable to reproduce a celebrated phenomenon in blood microcirculation known as Fåhræus effect, since its discovery by Robin Fåhræus (1929). This consists in a decaying of the relative hematocrit in small vessels as the vessel diameter decreases. The key point of the model is a formula, direct consequence of the basic principles of fluid dynamics, that links the relative hematocrit to the reservoir hematocrit and the vessel diameter, which confirms the observed behavior. To test the model we selected, among the few experiments carried on since then, those performed by Barbee and Cokelet (1971). The agreement is remarkable. An extended comparison is also carried out with a celebrated empirical formula proposed by Pries et al. (1992) to describe the same phenomenon. • Modeling of blood flow in medium–large microvessels. • Theoretical description of the Fåhræus effect. • Explicit formulas for H T as a function of H D. • Comparison with the Barbee–Cokelet experiments. [ABSTRACT FROM AUTHOR]