Blood Flow Modeling: The Fahræus–Lindqvist Effect
Blood flow in micro capillaries has specific features including concentration of red blood cells in the core region and lower apparent viscosity. Haynes’ theory discerns two zones: a constant hematocrit level core region and a cell-free annular zone. The decrease in the tube viscosity (Fahræus–Lindqvist effect) is addressed in Chebbi (Journal of Biological Physics, 2015). For given feed and tube hematocrit levels and temperature, the model provides the size of the core region and the decrease in viscosity. The results are in good agreement with experimental tube viscosity data and support Haynes’ theory. The model is extended to treat the case of bifurcation of a feeding vessel by including in addition hematocrit and mass balances, along with the Hagen-Poiseuille equation applied to each vessel to provide blood flow and hematocrit split ratios, along with the hematocrit levels and sizes of the core regions in the two daughter vessels.
Keywords - Blood Flow, Fahræus–Lindqvist Effect, Tube Viscosity, Haynes’ Theory, Cell-Free Layer, Bifurcation, Hematocrit, Split Ratios