[Importance of non-Newtonian rheologic properties of blood in erythrocyte transport].

The authors studied the global transport of red blood cells (RBC) in a stationary cylindrical tube flow. The human blood was considered as homogeneous fluid. For geometric and dynamic conditions fixed, the quantity of transported RBC was calculated using different models of constitutive equation: i) Newtonian model with apparent viscosity measured at 128 sec-1; ii) Landel's model for rigidified RBC suspension; iii) three non-Newtonian models (Casson law, power law and a relationship of Sisko). We showed that there was an optimum hematocrit for every model for which the quantity of transported RBC was maximum. The values of optimum hematocrit obtained for the non-Newtonian models varied in function of the tube radius and the pressure drop. It was equally observed that the optimum hematocrit was very small when the red blood cells were rigid. These theoretical results merit experimental studies and open the way to investigations of mechanical transport of RBC (global oxygen transport) under different types of flow conditions.