EFFECT OF COMBINED SHEAR,SECONDARY AND AXIAL FLOW OF BLOOD ON OXYGEN UPTAKE

The oxygen uptake of red blood cells (RBC) has been investigated in a blood flowing model in which defined shear and secondary flows are produced with blood flow direction perpendicular to the shear plane. The model consists of a Couette flow realized by means of two coaxial cylinders with gas permeable walls. The “venous” blood flows in the axial direction. In the annual gap shear and secondary flows (Taylor-vortices) are produced by rotation of the inner cylinder which determine the amount of oxygen uptake. Different blood Row regions and conditions (Taylor-, Reynolds-number, and shear rates) in regard to non-Newtonian behaviour of blood have been reported. An increase of Taylor-number from 100 to 300 results in a greater than four-fold increase in oxygen uptake. For Taylor-numbers lower than 100 the oxygen uptake is not significantly enhanced due to flow instabilities. This can be explained by non-Newtonian flow behaviour of blood and appearance of different flow regions. The results for normal whole blood are compared to those for water and for artificially regidified red cell membranes.