[Non-newtonian behavior of blood and parietal shear stress in a Poiseuille flow].

The authors study the blood flow in a cylindrical vessel with the consideration of the non-newtonian behaviour of blood. Supposing that the vessel's diameter and the blood velocity at the centre are known (measurable by a Doppler ultrasound velocimeter), we calculate the velocity profiles, flow rate, wall shear stress and shear rate, with 8 non-newtonian models, by a numerical method which allows us to solve the flow system for any non-newtonian fluid. The numerical results are compared with those obtained for a newtonian fluid which remains the most used model in clinical practice. This work shows the importance of the use of a realistic non-newtonian rheological relationship in the estimation of mechanical factors especially the wall shear stress in blood circulation.