Theory of non-Newtonian viscosity of blood at low shear rate—effect of rouleaux

Article type: Research Article

Authors: Murata, Tadayoshi

Affiliations: Department of Physics, Faculty of Science, Tokyo Metropolitan University, Setagaya-ku, Tokyo, Japan

Abstract: Non-Newtonian behavior of blood in which red cells aggregate to form rouleaux at very low shear rate are theoretically considered. The theory of coagulation in colloids is applied to the process of rouleaux formation. The expression of the average size of rouleaux in a dynamical equilibrium is obtained. It is shown that the average size of rouleaux decreases monotonously with increase in shear rate and is reduced to that given by Casson on some assumptions. The apparent viscosity and the shear stress–shear rate relationship for a dilute red cell suspension are also obtained. It is shown that the plots of square root of shear rate vs square root of shear stress lie on the curve whose asymptote is given by Casson’s equation. On some assumptions the relationship between shear stress and shear rate for a quasi-concentrated red cell suspension is obtained.

DOI: 10.3233/BIR-1976-13504

Journal: Biorheology, vol. 13, no. 5, pp. 287-296, 1976