Hydrodynamic interaction between two red blood cells in simple shear flow: its impact on the rheology of a semi-dilute suspension

摘要

Blood is a suspension of red blood cells (RBCs) and its rheology is important when discussing the physiology of the cardiovascular system. In this study,we performed a numerical investigation of the rheological properties of an RBC suspension from the dilute to semi-dilute regime. RBCs were modelled as a capsule with a two-dimensional hyperelastic membrane. Large deformation of the thin membrane was calculated by a finite element method. Due to the small size of the RBC, fluid motion around the RBC was assumed to follow Stokes flow and was solved by a boundary element method. In the dilute limit, cell-cell interactions were omitted and the bulk stress of the suspension was calculated by the stresslet generated on a single RBC. Interestingly, the effective shear viscosity of the dilute suspension decreased with increasing viscosity of the internal liquid. In the semidilute regime, cells can be considered as showing pairwise interactions. The effective shear viscosity of the semi-dilute suspension shows a quadratic increasewith respect to the volume fraction. These findings are important for understanding the complex phenomena of blood rheology.