Computational fluid dynamic studies of leukocyte adhesion effects on non-Newtonian blood flow through microvessels

The study of the effect of leukocyte adhesion on blood flow in small vessel s is of primary interest to understand the resistance changes in venular mi crocirculation. Available computational fluid dynamic studies provide infor mation on the effect of leukocyte adhesion when blood is considered as a ho mogeneous Newtonian fluid. In the present work we aim to understand the eff ect of leukocyte adhesion on the non-Newtonian Casson fluid flow of blood i n small venules; the Casson model represents the effect of red blood cell a ggregation. In our model the blood vessel is considered as a circular cylin der and the leukocyte is considered as a truncated spherical protrusion in the inner side of the blood vessel. The cases of single leukocyte adhesion and leukocyte pairs in positions aligned along the same side, and opposite sides of the vessel wall are considered. The Casson fluid parameters are ch osen for cat blood and human blood and comparisons are made for the effects of leukocyte adhesion in both species. Numerical simulations demonstrated that for a Casson fluid with hematocrit of 0.4 and flow rate Q = 0.072 nl/s , a single leukocyte increases flow resistance by 5% in a 32 mu m diameter and 100 mu m long vessel. For a smaller vessel of 18 mu m, the flow resista nce increases by 15%.